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Smart Cheater"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Smart Cheater</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>I guess there's not much point in reminding you that Nvodsk winters aren't exactly hot. That increased the popularity of the public transport dramatically. The route of bus <span class=\"tex-span\">62</span> has exactly <span class=\"tex-span\"><i>n</i></span> stops (stop <span class=\"tex-span\">1</span> goes first on its way and stop <span class=\"tex-span\"><i>n</i></span> goes last). The stops are positioned on a straight line and their coordinates are <span class=\"tex-span\">0 = <i>x</i><sub class=\"lower-index\">1</sub> < <i>x</i><sub class=\"lower-index\">2</sub> < ... < <i>x</i><sub class=\"lower-index\"><i>n</i></sub></span>. </p><p>Each day exactly <span class=\"tex-span\"><i>m</i></span> people use bus <span class=\"tex-span\">62</span>. For each person we know the number of the stop where he gets on the bus and the number of the stop where he gets off the bus. A ticket from stop <span class=\"tex-span\"><i>a</i></span> to stop <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>a</i> < <i>b</i></span>) costs <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>b</i></sub> - <i>x</i><sub class=\"lower-index\"><i>a</i></sub></span> rubles. However, the conductor can choose no more than one segment NOT TO SELL a ticket for. We mean that conductor should choose C and D (С <= D) and sell a ticket for the segments [<span class=\"tex-span\"><i>A</i></span>, <span class=\"tex-span\"><i>C</i></span>] and [<span class=\"tex-span\"><i>D</i></span>, <span class=\"tex-span\"><i>B</i></span>], or not sell the ticket at all. The conductor and the passenger divide the saved money between themselves equally. The conductor's \"untaxed income\" is sometimes interrupted by inspections that take place as the bus drives on some segment of the route located between two consecutive stops. The inspector fines the conductor by <span class=\"tex-span\"><i>c</i></span> rubles for each passenger who doesn't have the ticket for this route's segment.</p><p>You know the coordinated of all stops <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>; the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>); the fine <span class=\"tex-span\"><i>c</i></span>; and also <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> — the probability of inspection on segment between the <span class=\"tex-span\"><i>i</i></span>-th and the <span class=\"tex-span\"><i>i</i> + 1</span>-th stop. The conductor asked you to help him make a plan of selling tickets that maximizes the mathematical expectation of his profit.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>c</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 150 000</span>, <span class=\"tex-span\">1 ≤ <i>m</i> ≤ 300 000</span>, <span class=\"tex-span\">1 ≤ <i>c</i> ≤ 10 000</span>).</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> = 0</span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub> < <i>x</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>) — the coordinates of the stops on the bus's route.</p><p>The third line contains <span class=\"tex-span\"><i>n</i> - 1</span> integer <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the probability of inspection in percents on the segment between stop <span class=\"tex-span\"><i>i</i></span> and stop <span class=\"tex-span\"><i>i</i> + 1</span>.</p><p>Then follow <span class=\"tex-span\"><i>m</i></span> lines that describe the bus's passengers. Each line contains exactly two integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>) — the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the maximum expectation of the conductor's profit. Your answer will be considered correct if its absolute or relative error does not exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 6</sup></span>. </p><p>Namely: let's assume that your answer is <span class=\"tex-span\"><i>a</i></span>, and the answer of the jury is <span class=\"tex-span\"><i>b</i></span>. The checker program will consider your answer correct, if <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/c97ba2000ebfad962bff7ffd8d043594f5ae1086.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 10<br/>0 10 100<br/>100 0<br/>1 2<br/>2 3<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>90.000000000<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 8 187<br/>0 10 30 70 150 310 630 1270 2550 51100<br/>13 87 65 0 100 44 67 3 4<br/>1 10<br/>2 9<br/>3 8<br/>1 5<br/>6 10<br/>2 7<br/>4 10<br/>4 5<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>76859.990000000<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample:</p><p>The first and third passengers get tickets from stop <span class=\"tex-span\">1</span> to stop <span class=\"tex-span\">2</span>. The second passenger doesn't get a ticket. There always is inspection on the segment <span class=\"tex-span\">1</span>-<span class=\"tex-span\">2</span> but both passengers have the ticket for it. There never is an inspection on the segment <span class=\"tex-span\">2</span>-<span class=\"tex-span\">3</span>, that's why the second passenger gets away with the cheating. Our total profit is <span class=\"tex-span\">(0 + 90 / 2 + 90 / 2) = 90</span>.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"e3d41448e2f8a2f0b2955abd057aad32\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"f225978bcf2bc2c6e3a0eaadf901704944fbb6e3\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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}\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_849c0684cead7e8f42fa2c77bb1bb743d4f60884\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Smart Cheater</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>I guess there's not much point in reminding you that Nvodsk winters aren't exactly hot. That increased the popularity of the public transport dramatically. The route of bus <span class=\"tex-span\">62</span> has exactly <span class=\"tex-span\"><i>n</i></span> stops (stop <span class=\"tex-span\">1</span> goes first on its way and stop <span class=\"tex-span\"><i>n</i></span> goes last). The stops are positioned on a straight line and their coordinates are <span class=\"tex-span\">0 = <i>x</i><sub class=\"lower-index\">1</sub> < <i>x</i><sub class=\"lower-index\">2</sub> < ... < <i>x</i><sub class=\"lower-index\"><i>n</i></sub></span>. </p><p>Each day exactly <span class=\"tex-span\"><i>m</i></span> people use bus <span class=\"tex-span\">62</span>. For each person we know the number of the stop where he gets on the bus and the number of the stop where he gets off the bus. A ticket from stop <span class=\"tex-span\"><i>a</i></span> to stop <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>a</i> < <i>b</i></span>) costs <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>b</i></sub> - <i>x</i><sub class=\"lower-index\"><i>a</i></sub></span> rubles. However, the conductor can choose no more than one segment NOT TO SELL a ticket for. We mean that conductor should choose C and D (С <= D) and sell a ticket for the segments [<span class=\"tex-span\"><i>A</i></span>, <span class=\"tex-span\"><i>C</i></span>] and [<span class=\"tex-span\"><i>D</i></span>, <span class=\"tex-span\"><i>B</i></span>], or not sell the ticket at all. The conductor and the passenger divide the saved money between themselves equally. The conductor's "untaxed income" is sometimes interrupted by inspections that take place as the bus drives on some segment of the route located between two consecutive stops. The inspector fines the conductor by <span class=\"tex-span\"><i>c</i></span> rubles for each passenger who doesn't have the ticket for this route's segment.</p><p>You know the coordinated of all stops <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>; the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>); the fine <span class=\"tex-span\"><i>c</i></span>; and also <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> — the probability of inspection on segment between the <span class=\"tex-span\"><i>i</i></span>-th and the <span class=\"tex-span\"><i>i</i> + 1</span>-th stop. The conductor asked you to help him make a plan of selling tickets that maximizes the mathematical expectation of his profit.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>c</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 150 000</span>, <span class=\"tex-span\">1 ≤ <i>m</i> ≤ 300 000</span>, <span class=\"tex-span\">1 ≤ <i>c</i> ≤ 10 000</span>).</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> = 0</span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub> < <i>x</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>) — the coordinates of the stops on the bus's route.</p><p>The third line contains <span class=\"tex-span\"><i>n</i> - 1</span> integer <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the probability of inspection in percents on the segment between stop <span class=\"tex-span\"><i>i</i></span> and stop <span class=\"tex-span\"><i>i</i> + 1</span>.</p><p>Then follow <span class=\"tex-span\"><i>m</i></span> lines that describe the bus's passengers. Each line contains exactly two integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>) — the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the maximum expectation of the conductor's profit. Your answer will be considered correct if its absolute or relative error does not exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 6</sup></span>. </p><p>Namely: let's assume that your answer is <span class=\"tex-span\"><i>a</i></span>, and the answer of the jury is <span class=\"tex-span\"><i>b</i></span>. The checker program will consider your answer correct, if <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/c97ba2000ebfad962bff7ffd8d043594f5ae1086.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" />.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 10<br />0 10 100<br />100 0<br />1 2<br />2 3<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>90.000000000<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 8 187<br />0 10 30 70 150 310 630 1270 2550 51100<br />13 87 65 0 100 44 67 3 4<br />1 10<br />2 9<br />3 8<br />1 5<br />6 10<br />2 7<br />4 10<br />4 5<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>76859.990000000<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample:</p><p>The first and third passengers get tickets from stop <span class=\"tex-span\">1</span> to stop <span class=\"tex-span\">2</span>. The second passenger doesn't get a ticket. There always is inspection on the segment <span class=\"tex-span\">1</span>-<span class=\"tex-span\">2</span> but both passengers have the ticket for it. There never is an inspection on the segment <span class=\"tex-span\">2</span>-<span class=\"tex-span\">3</span>, that's why the second passenger gets away with the cheating. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:20</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n\r\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div>\r\n\r\n\n <div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='b95b03959f378690a7b97e71cd66874f'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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Mission Impassable"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Mission Impassable</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Market stalls now have the long-awaited game The Colder Scrools V: Nvodsk. The game turned out to be difficult as hell and most students can't complete the last quest (\"We don't go to Nvodsk...\"). That threatened winter exams. The rector already started to wonder whether he should postpone the winter exams till April (in fact, he wanted to complete the quest himself). But all of a sudden a stranger appeared at the door of his office. \"Good afternoon. My name is Chuck and I solve any problems\" — he said.</p><p>And here they are sitting side by side but still they can't complete the mission. The thing is, to kill the final boss one should prove one's perfect skills in the art of managing letters. One should be a real magician to do that. And can you imagine what happens when magicians start competing... </p><p>But let's put it more formally: you are given a string and a set of integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. You are allowed to choose any substring that is a palindrome and delete it. At that we receive some number of points equal to <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub></span>, where <span class=\"tex-span\"><i>k</i></span> is the length of the deleted palindrome. For some <span class=\"tex-span\"><i>k</i></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub> = </span>-1, which means that deleting palindrome strings of such length is <span class=\"tex-font-style-bf\">forbidden</span>. After a substring is deleted, the remaining part \"shifts together\", that is, at no moment of time the string has gaps. The process is repeated while the string has at least one palindrome substring that can be deleted. All gained points are summed up.</p><p>Determine what maximum number of points can be earned.</p><p>\"Oh\" — said Chuck, raising from the chair, — \"I used to love deleting palindromes, just like you, but one day I took an arrow in the Knee\".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>l</i></span> (<span class=\"tex-span\">1 ≤ <i>l</i> ≤ 150</span>) — the length of the string.</p><p>The second line contains exactly <span class=\"tex-span\"><i>l</i></span> integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub></span> (<span class=\"tex-span\"> - 1 ≤ <i>a</i><sub class=\"lower-index\"><i>k</i></sub> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the points a player gains for deleting.</p><p>The third line contains exactly <span class=\"tex-span\"><i>l</i></span> lowercase Latin letters — the original string from which a player can delete palindromes. The line contains no other characters apart from the newline character at the end of the string.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single number — the maximum number of points one can gain if he plays on the given string.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>7<br/>-1 -1 -1 -1 -1 -1 -1<br/>abacaba<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>7<br/>1 -1 -1 -1 -1 -1 -1<br/>abacaba<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>7<br/>1 5 -1 -1 -1 -1 10<br/>abacaba<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>16<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample we cannot delete any substring, so the best result is <span class=\"tex-span\">0</span>. In the second sample we are allowed to delete only those palindromes whose length equals <span class=\"tex-span\">1</span>, thus, if we delete the whole string, we get <span class=\"tex-span\">7</span> points. In the third sample the optimal strategy is: first we delete character <span class=\"tex-font-style-tt\">c</span>, then string <span class=\"tex-font-style-tt\">aa</span>, then <span class=\"tex-font-style-tt\">bb</span>, and the last one <span class=\"tex-font-style-tt\">aa</span>. At that we get <span class=\"tex-span\">1 + 3 * 5 = 16</span> points.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"34c3d3f5a81b72dd15b6684ff580f30b\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"f225978bcf2bc2c6e3a0eaadf901704944fbb6e3\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/150\">Codeforces Round 107 (Div. 1)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/150/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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\"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3899\" title=\"Codeforces Round #107\" target=\"_blank\">Codeforces Round #107</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"3593:3594\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"https://codeforces.com/blog/entry/3905?locale=en\" title=\"Tutorial\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(en)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img 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data-uuid=\"ps_3760f63f504df751c47ea57df2a5714880196c9f\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Mission Impassable</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Market stalls now have the long-awaited game The Colder Scrools V: Nvodsk. The game turned out to be difficult as hell and most students can't complete the last quest ("We don't go to Nvodsk..."). That threatened winter exams. The rector already started to wonder whether he should postpone the winter exams till April (in fact, he wanted to complete the quest himself). But all of a sudden a stranger appeared at the door of his office. "Good afternoon. My name is Chuck and I solve any problems" — he said.</p><p>And here they are sitting side by side but still they can't complete the mission. The thing is, to kill the final boss one should prove one's perfect skills in the art of managing letters. One should be a real magician to do that. And can you imagine what happens when magicians start competing... </p><p>But let's put it more formally: you are given a string and a set of integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. You are allowed to choose any substring that is a palindrome and delete it. At that we receive some number of points equal to <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub></span>, where <span class=\"tex-span\"><i>k</i></span> is the length of the deleted palindrome. For some <span class=\"tex-span\"><i>k</i></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub> = </span>-1, which means that deleting palindrome strings of such length is <span class=\"tex-font-style-bf\">forbidden</span>. After a substring is deleted, the remaining part "shifts together", that is, at no moment of time the string has gaps. The process is repeated while the string has at least one palindrome substring that can be deleted. All gained points are summed up.</p><p>Determine what maximum number of points can be earned.</p><p>"Oh" — said Chuck, raising from the chair, — "I used to love deleting palindromes, just like you, but one day I took an arrow in the Knee".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>l</i></span> (<span class=\"tex-span\">1 ≤ <i>l</i> ≤ 150</span>) — the length of the string.</p><p>The second line contains exactly <span class=\"tex-span\"><i>l</i></span> integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>k</i></sub></span> (<span class=\"tex-span\"> - 1 ≤ <i>a</i><sub class=\"lower-index\"><i>k</i></sub> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the points a player gains for deleting.</p><p>The third line contains exactly <span class=\"tex-span\"><i>l</i></span> lowercase Latin letters — the original string from which a player can delete palindromes. The line contains no other characters apart from the newline character at the end of the string.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single number — the maximum number of points one can gain if he plays on the given string.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>7<br />-1 -1 -1 -1 -1 -1 -1<br />abacaba<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>7<br />1 -1 -1 -1 -1 -1 -1<br />abacaba<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>7<br />1 5 -1 -1 -1 -1 10<br />abacaba<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>16<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample we cannot delete any substring, so the best result is <span class=\"tex-span\">0</span>. In the second sample we are allowed to delete only those palindromes whose length equals <span class=\"tex-span\">1</span>, thus, if we delete the whole string, we get <span class=\"tex-span\">7</span> points. In the third sample the optimal strategy is: first we delete character <span class=\"tex-font-style-tt\">c</span>, then string <span class=\"tex-font-style-tt\">aa</span>, then <span class=\"tex-font-style-tt\">bb</span>, and the last one <span class=\"tex-font-style-tt\">aa</span>. At that we get <span class=\"tex-span\">1 + 3 * 5 = 16</span> points.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=D]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n $problem.find(\"a.view-changes\").click(function() {\r\n $.post(\"/data/diff\", {action: \"getDiff\", a: previousStatementText, b: statementText}, function (result) {\r\n if (result[\"success\"] === \"true\") {\r\n 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: 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class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div>\r\n\r\n\n <div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='b95b03959f378690a7b97e71cd66874f'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":747,"cells":{"problem_id":{"kind":"string","value":"150E"},"contest":{"kind":"string","value":"150"},"problem":{"kind":"string","value":"E"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"E. Freezing with Style"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Freezing with Style</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>7 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>This winter is so... well, you've got the idea :-) The Nvodsk road system can be represented as <span class=\"tex-span\"><i>n</i></span> junctions connected with <span class=\"tex-span\"><i>n</i> - 1</span> bidirectional roads so that there is a path between any two junctions. The organizers of some event want to choose a place to accommodate the participants (junction <span class=\"tex-span\"><i>v</i></span>), and the place to set up the contests (junction <span class=\"tex-span\"><i>u</i></span>). Besides, at the one hand, they want the participants to walk about the city and see the neighbourhood (that's why the distance between <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> should be no less than <span class=\"tex-span\"><i>l</i></span>). On the other hand, they don't want the participants to freeze (so the distance between <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> should be no more than <span class=\"tex-span\"><i>r</i></span>). Besides, for every street we know its beauty — some integer from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup></span>. Your task is to choose the path that fits in the length limits and has the largest average beauty. We shall define the average beauty as a median of sequence of the beauties of all roads along the path.</p><p>We can put it more formally like that: let there be a path with the length <span class=\"tex-span\"><i>k</i></span>. Let <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> be a non-decreasing sequence that contains exactly <span class=\"tex-span\"><i>k</i></span> elements. Each number occurs there exactly the number of times a road with such beauty occurs along on path. We will represent the path median as number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">⌊<i>k</i> / 2⌋</sub></span>, assuming that <span class=\"tex-font-style-bf\">indexation starting from zero</span> is used. <span class=\"tex-span\">⌊<i>x</i>⌋</span> — is number <span class=\"tex-span\"><i>х</i></span>, rounded down to the nearest integer.</p><p>For example, if <span class=\"tex-span\"><i>a</i> = {0, 5, 12}</span>, then the median equals to <span class=\"tex-span\">5</span>, and if <span class=\"tex-span\"><i>a</i> = {0, 5, 7, 12}</span>, then the median is number <span class=\"tex-span\">7</span>.</p><p>It is guaranteed that there will be at least one path with the suitable quantity of roads.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>l</i></span>, <span class=\"tex-span\"><i>r</i></span> (<span class=\"tex-span\">1 ≤ <i>l</i> ≤ <i>r</i> < <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>).</p><p>Next <span class=\"tex-span\"><i>n</i> - 1</span> lines contain descriptions of roads of the Nvodsk, each line contains three integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub>, <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>, <span class=\"tex-span\">0 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≠ <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>) — junctions <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> are connected with a street whose beauty equals <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print two integers — numbers of the junctions, where to accommodate the participants and set up the contests, correspondingly. If there are multiple optimal variants, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>6 3 4<br/>1 2 1<br/>2 3 1<br/>3 4 1<br/>4 5 1<br/>5 6 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4 1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6 3 4<br/>1 2 1<br/>2 3 1<br/>3 4 1<br/>4 5 2<br/>5 6 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6 3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 1 4<br/>1 2 1<br/>1 3 4<br/>3 4 7<br/>3 5 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4 3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>8 3 6<br/>1 2 9<br/>2 3 7<br/>3 4 7<br/>4 5 8<br/>5 8 2<br/>3 6 3<br/>2 7 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5 1<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample all roads have the same beauty. That means that all paths of the positive length have the same median. Thus, any path with length from <span class=\"tex-span\">3</span> to <span class=\"tex-span\">4</span>, inclusive will be valid for us.</p><p>In the second sample the city looks like that: 1 - 2 - 3 - 4 - 5 - 6. Two last roads are more valuable and we should choose any path that contains both of them and has the suitable length. 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class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Freezing with Style</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>7 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>This winter is so... well, you've got the idea :-) The Nvodsk road system can be represented as <span class=\"tex-span\"><i>n</i></span> junctions connected with <span class=\"tex-span\"><i>n</i> - 1</span> bidirectional roads so that there is a path between any two junctions. The organizers of some event want to choose a place to accommodate the participants (junction <span class=\"tex-span\"><i>v</i></span>), and the place to set up the contests (junction <span class=\"tex-span\"><i>u</i></span>). Besides, at the one hand, they want the participants to walk about the city and see the neighbourhood (that's why the distance between <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> should be no less than <span class=\"tex-span\"><i>l</i></span>). On the other hand, they don't want the participants to freeze (so the distance between <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> should be no more than <span class=\"tex-span\"><i>r</i></span>). Besides, for every street we know its beauty — some integer from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup></span>. Your task is to choose the path that fits in the length limits and has the largest average beauty. We shall define the average beauty as a median of sequence of the beauties of all roads along the path.</p><p>We can put it more formally like that: let there be a path with the length <span class=\"tex-span\"><i>k</i></span>. Let <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> be a non-decreasing sequence that contains exactly <span class=\"tex-span\"><i>k</i></span> elements. Each number occurs there exactly the number of times a road with such beauty occurs along on path. We will represent the path median as number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">⌊<i>k</i> / 2⌋</sub></span>, assuming that <span class=\"tex-font-style-bf\">indexation starting from zero</span> is used. <span class=\"tex-span\">⌊<i>x</i>⌋</span> — is number <span class=\"tex-span\"><i>х</i></span>, rounded down to the nearest integer.</p><p>For example, if <span class=\"tex-span\"><i>a</i> = {0, 5, 12}</span>, then the median equals to <span class=\"tex-span\">5</span>, and if <span class=\"tex-span\"><i>a</i> = {0, 5, 7, 12}</span>, then the median is number <span class=\"tex-span\">7</span>.</p><p>It is guaranteed that there will be at least one path with the suitable quantity of roads.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>l</i></span>, <span class=\"tex-span\"><i>r</i></span> (<span class=\"tex-span\">1 ≤ <i>l</i> ≤ <i>r</i> < <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>).</p><p>Next <span class=\"tex-span\"><i>n</i> - 1</span> lines contain descriptions of roads of the Nvodsk, each line contains three integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub>, <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>, <span class=\"tex-span\">0 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≠ <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>) — junctions <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> are connected with a street whose beauty equals <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print two integers — numbers of the junctions, where to accommodate the participants and set up the contests, correspondingly. If there are multiple optimal variants, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>6 3 4<br />1 2 1<br />2 3 1<br />3 4 1<br />4 5 1<br />5 6 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4 1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6 3 4<br />1 2 1<br />2 3 1<br />3 4 1<br />4 5 2<br />5 6 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6 3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 1 4<br />1 2 1<br />1 3 4<br />3 4 7<br />3 5 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4 3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>8 3 6<br />1 2 9<br />2 3 7<br />3 4 7<br />4 5 8<br />5 8 2<br />3 6 3<br />2 7 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5 1<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample all roads have the same beauty. That means that all paths of the positive length have the same median. Thus, any path with length from <span class=\"tex-span\">3</span> to <span class=\"tex-span\">4</span>, inclusive will be valid for us.</p><p>In the second sample the city looks like that: 1 - 2 - 3 - 4 - 5 - 6. Two last roads are more valuable and we should choose any path that contains both of them and has the suitable length. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:20</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n\r\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div>\r\n\r\n\n <div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='b95b03959f378690a7b97e71cd66874f'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":748,"cells":{"problem_id":{"kind":"string","value":"151A"},"contest":{"kind":"string","value":"151"},"problem":{"kind":"string","value":"A"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"A. Soft Drinking"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Soft Drinking</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>This winter is so cold in Nvodsk! A group of <span class=\"tex-span\"><i>n</i></span> friends decided to buy <span class=\"tex-span\"><i>k</i></span> bottles of a soft drink called \"Take-It-Light\" to warm up a bit. Each bottle has <span class=\"tex-span\"><i>l</i></span> milliliters of the drink. Also they bought <span class=\"tex-span\"><i>c</i></span> limes and cut each of them into <span class=\"tex-span\"><i>d</i></span> slices. After that they found <span class=\"tex-span\"><i>p</i></span> grams of salt.</p><p>To make a toast, each friend needs <span class=\"tex-span\"><i>nl</i></span> milliliters of the drink, a slice of lime and <span class=\"tex-span\"><i>np</i></span> grams of salt. The friends want to make as many toasts as they can, provided they all drink the same amount. How many toasts can each friend make?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first and only line contains <span class=\"tex-font-style-bf\">positive</span> integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>k</i></span>, <span class=\"tex-span\"><i>l</i></span>, <span class=\"tex-span\"><i>c</i></span>, <span class=\"tex-span\"><i>d</i></span>, <span class=\"tex-span\"><i>p</i></span>, <span class=\"tex-span\"><i>nl</i></span>, <span class=\"tex-span\"><i>np</i></span>, not exceeding <span class=\"tex-span\">1000</span> and no less than <span class=\"tex-span\">1</span>. The numbers are separated by exactly one space.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single integer — the number of toasts each friend can make.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 4 5 10 8 100 3 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 100 10 1 19 90 4 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 1000 1000 25 23 1 50 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample: </p><p>Overall the friends have <span class=\"tex-span\">4 * 5 = 20</span> milliliters of the drink, it is enough to make <span class=\"tex-span\">20 / 3 = 6</span> toasts. The limes are enough for <span class=\"tex-span\">10 * 8 = 80</span> toasts and the salt is enough for <span class=\"tex-span\">100 / 1 = 100</span> toasts. However, there are 3 friends in the group, so the answer is <span class=\"tex-span\"><i>min</i>(6, 80, 100) / 3 = 2</span>.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"163d4c2310d2f97ea83b15471bd22589\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"ea8e0bdb7b51062f470d1988db24be37dd2a76af\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/151\">Codeforces Round 107 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='163d4c2310d2f97ea83b15471bd22589'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/151/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = $(this).hasClass(\"la-angle-right\");\r\n const params = {\r\n action: \"setCollapsed\",\r\n sidebarFrameSimpleClassName: \"ContestVirtualFrame\",\r\n collapsed\r\n };\r\n $.each($target[0].attributes, function(i, a) {\r\n const name = a.name;\r\n if (name.startsWith(\"data-extra-key-\")) {\r\n const key = a.value;\r\n const keyIndex = parseInt(name.substring(\"data-extra-key-\".length));\r\n const value = $target.attr(\"data-extra-value-\" + keyIndex);\r\n params[key] = value;\r\n }\r\n });\r\n $.post(dataPageUrl, params, function (result) {\r\n if (result[\"success\"] !== \"true\") {\r\n Codeforces.showMessage(\"Failed to save collapsed state.\");\r\n }\r\n }, \"json\");\r\n return false;\r\n });\r\n })\r\n </script>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Problem tags\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\"padding: 0.5em;\">\r\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Implementation problems, programming technics, simulation\">\r\n implementation\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Mathematics including integration, differential equations, etc\">\r\n math\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *800\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='163d4c2310d2f97ea83b15471bd22589'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"934\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='163d4c2310d2f97ea83b15471bd22589'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"934\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3899\" title=\"Codeforces Round #107\" target=\"_blank\">Codeforces Round #107</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"365:366\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3905\" title=\"Codeforces Round #107. Tutorial.\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"946:947\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/151\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/151/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/151/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/151/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/151/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/151/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/151/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/151/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const nodeToText = function (node, pre) {\r\n let result = [];\r\n\r\n if (node.tagName === \"SCRIPT\" || node.tagName === \"math\"\r\n || (node.classList && node.classList.contains(\"input-output-copier\")))\r\n return [];\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(OPENING_SPACE);\r\n }\r\n\r\n if (node.nodeType === Node.TEXT_NODE) {\r\n let s = node.textContent;\r\n if (!pre) {\r\n s = s.replace(/\\s+/g, \" \");\r\n }\r\n if (s.length > 0) {\r\n result.push(s);\r\n }\r\n }\r\n\r\n if (pre && node.tagName === \"BR\") {\r\n result.push(\"\\n\");\r\n }\r\n\r\n node.childNodes.forEach(function (child) {\r\n result.push(nodeToText(child, node.tagName === \"PRE\").join(\"\"));\r\n });\r\n\r\n if (node.tagName === \"DIV\"\r\n || node.tagName === \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_263a340083604e4632256a711301cbf6cb63b326\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Soft Drinking</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>This winter is so cold in Nvodsk! A group of <span class=\"tex-span\"><i>n</i></span> friends decided to buy <span class=\"tex-span\"><i>k</i></span> bottles of a soft drink called "Take-It-Light" to warm up a bit. Each bottle has <span class=\"tex-span\"><i>l</i></span> milliliters of the drink. Also they bought <span class=\"tex-span\"><i>c</i></span> limes and cut each of them into <span class=\"tex-span\"><i>d</i></span> slices. After that they found <span class=\"tex-span\"><i>p</i></span> grams of salt.</p><p>To make a toast, each friend needs <span class=\"tex-span\"><i>nl</i></span> milliliters of the drink, a slice of lime and <span class=\"tex-span\"><i>np</i></span> grams of salt. The friends want to make as many toasts as they can, provided they all drink the same amount. How many toasts can each friend make?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first and only line contains <span class=\"tex-font-style-bf\">positive</span> integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>k</i></span>, <span class=\"tex-span\"><i>l</i></span>, <span class=\"tex-span\"><i>c</i></span>, <span class=\"tex-span\"><i>d</i></span>, <span class=\"tex-span\"><i>p</i></span>, <span class=\"tex-span\"><i>nl</i></span>, <span class=\"tex-span\"><i>np</i></span>, not exceeding <span class=\"tex-span\">1000</span> and no less than <span class=\"tex-span\">1</span>. The numbers are separated by exactly one space.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single integer — the number of toasts each friend can make.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 4 5 10 8 100 3 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 100 10 1 19 90 4 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 1000 1000 25 23 1 50 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample: </p><p>Overall the friends have <span class=\"tex-span\">4 * 5 = 20</span> milliliters of the drink, it is enough to make <span class=\"tex-span\">20 / 3 = 6</span> toasts. The limes are enough for <span class=\"tex-span\">10 * 8 = 80</span> toasts and the salt is enough for <span class=\"tex-span\">100 / 1 = 100</span> toasts. However, there are 3 friends in the group, so the answer is <span class=\"tex-span\"><i>min</i>(6, 80, 100) / 3 = 2</span>.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=A]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n $problem.find(\"a.view-changes\").click(function() {\r\n $.post(\"/data/diff\", {action: \"getDiff\", a: previousStatementText, b: statementText}, function (result) {\r\n if 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:19</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='7e06e3404f9e0c1af534082ddbd4b3d4'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":749,"cells":{"problem_id":{"kind":"string","value":"151B"},"contest":{"kind":"string","value":"151"},"problem":{"kind":"string","value":"B"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"B. Phone Numbers"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Phone Numbers</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Winters are just damn freezing cold in Nvodsk! That's why a group of <span class=\"tex-span\"><i>n</i></span> friends prefers to take a taxi, order a pizza and call girls. The phone numbers in the city consist of three pairs of digits (for example, 12-34-56). Each friend has a phonebook of size <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (that's the number of phone numbers). We know that taxi numbers consist of six identical digits (for example, 22-22-22), the numbers of pizza deliveries should necessarily be decreasing sequences of six different digits (for example, 98-73-21), all other numbers are the girls' numbers.</p><p>You are given your friends' phone books. Calculate which friend is best to go to when you are interested in each of those things (who has maximal number of phone numbers of each type). </p><p>If the phone book of one person contains some number two times, you should count it <span class=\"tex-font-style-bf\">twice</span>. That is, each number should be taken into consideration the number of times it occurs in the phone book.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>) — the number of friends. </p><p>Then follow <span class=\"tex-span\"><i>n</i></span> data blocks that describe each friend's phone books. Each block is presented in the following form: first goes the line that contains integer <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> and string <span class=\"tex-span\"><i>name</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the number of phone numbers in the phone book of the <span class=\"tex-span\"><i>i</i></span>-th friend and the name of the <span class=\"tex-span\"><i>i</i></span>-th friend. The name is a non-empty sequence of uppercase and lowercase Latin letters, containing no more than <span class=\"tex-span\">20</span> characters. Next <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> lines contain numbers as \"XX-XX-XX\", where X is arbitrary digits from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">9</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the phrase \"<span class=\"tex-font-style-tt\">If you want to call a taxi, you should call: </span>\". Then print names of all friends whose phone books contain maximal number of taxi phone numbers. </p><p>In the second line print the phrase \"<span class=\"tex-font-style-tt\">If you want to order a pizza, you should call: </span>\". Then print names of all friends who have maximal number of pizza phone numbers. </p><p>In the third line print the phrase \"<span class=\"tex-font-style-tt\">If you want to go to a cafe with a wonderful girl, you should call: </span>\". Then print names of all friends who have maximal number of girls' phone numbers. </p><p>Print the names in the order in which <span class=\"tex-font-style-bf\">they are given in the input data</span>. Separate two consecutive names with a comma and a space. Each line should end with exactly one point. For clarifications concerning the output form, see sample tests. It is necessary that you <span class=\"tex-font-style-bf\">follow the output form strictly</span>. Extra spaces are not allowed.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4<br/>2 Fedorov<br/>22-22-22<br/>98-76-54<br/>3 Melnikov<br/>75-19-09<br/>23-45-67<br/>99-99-98<br/>7 Rogulenko<br/>22-22-22<br/>11-11-11<br/>33-33-33<br/>44-44-44<br/>55-55-55<br/>66-66-66<br/>95-43-21<br/>3 Kaluzhin<br/>11-11-11<br/>99-99-99<br/>98-65-32<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Rogulenko.<br/>If you want to order a pizza, you should call: Fedorov, Rogulenko, Kaluzhin.<br/>If you want to go to a cafe with a wonderful girl, you should call: Melnikov.<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br/>5 Gleb<br/>66-66-66<br/>55-55-55<br/>01-01-01<br/>65-43-21<br/>12-34-56<br/>3 Serega<br/>55-55-55<br/>87-65-43<br/>65-55-21<br/>5 Melnik<br/>12-42-12<br/>87-73-01<br/>36-04-12<br/>88-12-22<br/>82-11-43<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Gleb.<br/>If you want to order a pizza, you should call: Gleb, Serega.<br/>If you want to go to a cafe with a wonderful girl, you should call: Melnik.<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br/>3 Kulczynski<br/>22-22-22<br/>65-43-21<br/>98-12-00<br/>4 Pachocki<br/>11-11-11<br/>11-11-11<br/>11-11-11<br/>98-76-54<br/>0 Smietanka<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Pachocki.<br/>If you want to order a pizza, you should call: Kulczynski, Pachocki.<br/>If you want to go to a cafe with a wonderful girl, you should call: Kulczynski.<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you are given four friends. <span class=\"tex-font-style-tt\">Fedorov</span>'s phone book contains one taxi number and one pizza delivery number, <span class=\"tex-font-style-tt\">Melnikov</span>'s phone book only has <span class=\"tex-span\">3</span> numbers of girls, <span class=\"tex-font-style-tt\">Rogulenko</span>'s one has <span class=\"tex-span\">6</span> taxi numbers and one pizza delivery number, <span class=\"tex-font-style-tt\">Kaluzhin</span>'s one contains <span class=\"tex-span\">2</span> taxi numbers and one pizza delivery number.</p><p>Thus, if you need to order a taxi, you should obviously call <span class=\"tex-font-style-tt\">Rogulenko</span>, if you need to order a pizza you should call anybody of the following: <span class=\"tex-font-style-tt\">Rogulenko</span>, <span class=\"tex-font-style-tt\">Fedorov</span>, <span class=\"tex-font-style-tt\">Kaluzhin</span> (each of them has one number). <span class=\"tex-font-style-tt\">Melnikov</span> has maximal number of phone numbers of girls. </p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; 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Phone Numbers</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Winters are just damn freezing cold in Nvodsk! That's why a group of <span class=\"tex-span\"><i>n</i></span> friends prefers to take a taxi, order a pizza and call girls. The phone numbers in the city consist of three pairs of digits (for example, 12-34-56). Each friend has a phonebook of size <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (that's the number of phone numbers). We know that taxi numbers consist of six identical digits (for example, 22-22-22), the numbers of pizza deliveries should necessarily be decreasing sequences of six different digits (for example, 98-73-21), all other numbers are the girls' numbers.</p><p>You are given your friends' phone books. Calculate which friend is best to go to when you are interested in each of those things (who has maximal number of phone numbers of each type). </p><p>If the phone book of one person contains some number two times, you should count it <span class=\"tex-font-style-bf\">twice</span>. That is, each number should be taken into consideration the number of times it occurs in the phone book.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>) — the number of friends. </p><p>Then follow <span class=\"tex-span\"><i>n</i></span> data blocks that describe each friend's phone books. Each block is presented in the following form: first goes the line that contains integer <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> and string <span class=\"tex-span\"><i>name</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the number of phone numbers in the phone book of the <span class=\"tex-span\"><i>i</i></span>-th friend and the name of the <span class=\"tex-span\"><i>i</i></span>-th friend. The name is a non-empty sequence of uppercase and lowercase Latin letters, containing no more than <span class=\"tex-span\">20</span> characters. Next <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> lines contain numbers as "XX-XX-XX", where X is arbitrary digits from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">9</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the phrase "<span class=\"tex-font-style-tt\">If you want to call a taxi, you should call: </span>". Then print names of all friends whose phone books contain maximal number of taxi phone numbers. </p><p>In the second line print the phrase "<span class=\"tex-font-style-tt\">If you want to order a pizza, you should call: </span>". Then print names of all friends who have maximal number of pizza phone numbers. </p><p>In the third line print the phrase "<span class=\"tex-font-style-tt\">If you want to go to a cafe with a wonderful girl, you should call: </span>". Then print names of all friends who have maximal number of girls' phone numbers. </p><p>Print the names in the order in which <span class=\"tex-font-style-bf\">they are given in the input data</span>. Separate two consecutive names with a comma and a space. Each line should end with exactly one point. For clarifications concerning the output form, see sample tests. It is necessary that you <span class=\"tex-font-style-bf\">follow the output form strictly</span>. Extra spaces are not allowed.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4<br />2 Fedorov<br />22-22-22<br />98-76-54<br />3 Melnikov<br />75-19-09<br />23-45-67<br />99-99-98<br />7 Rogulenko<br />22-22-22<br />11-11-11<br />33-33-33<br />44-44-44<br />55-55-55<br />66-66-66<br />95-43-21<br />3 Kaluzhin<br />11-11-11<br />99-99-99<br />98-65-32<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Rogulenko.<br />If you want to order a pizza, you should call: Fedorov, Rogulenko, Kaluzhin.<br />If you want to go to a cafe with a wonderful girl, you should call: Melnikov.<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br />5 Gleb<br />66-66-66<br />55-55-55<br />01-01-01<br />65-43-21<br />12-34-56<br />3 Serega<br />55-55-55<br />87-65-43<br />65-55-21<br />5 Melnik<br />12-42-12<br />87-73-01<br />36-04-12<br />88-12-22<br />82-11-43<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Gleb.<br />If you want to order a pizza, you should call: Gleb, Serega.<br />If you want to go to a cafe with a wonderful girl, you should call: Melnik.<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br />3 Kulczynski<br />22-22-22<br />65-43-21<br />98-12-00<br />4 Pachocki<br />11-11-11<br />11-11-11<br />11-11-11<br />98-76-54<br />0 Smietanka<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>If you want to call a taxi, you should call: Pachocki.<br />If you want to order a pizza, you should call: Kulczynski, Pachocki.<br />If you want to go to a cafe with a wonderful girl, you should call: Kulczynski.<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you are given four friends. <span class=\"tex-font-style-tt\">Fedorov</span>'s phone book contains one taxi number and one pizza delivery number, <span class=\"tex-font-style-tt\">Melnikov</span>'s phone book only has <span class=\"tex-span\">3</span> numbers of girls, <span class=\"tex-font-style-tt\">Rogulenko</span>'s one has <span class=\"tex-span\">6</span> taxi numbers and one pizza delivery number, <span class=\"tex-font-style-tt\">Kaluzhin</span>'s one contains <span class=\"tex-span\">2</span> taxi numbers and one pizza delivery number.</p><p>Thus, if you need to order a taxi, you should obviously call <span class=\"tex-font-style-tt\">Rogulenko</span>, if you need to order a pizza you should call anybody of the following: <span class=\"tex-font-style-tt\">Rogulenko</span>, <span class=\"tex-font-style-tt\">Fedorov</span>, <span class=\"tex-font-style-tt\">Kaluzhin</span> (each of them has one number). <span class=\"tex-font-style-tt\">Melnikov</span> has maximal number of phone numbers of girls. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='7e06e3404f9e0c1af534082ddbd4b3d4'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":750,"cells":{"problem_id":{"kind":"string","value":"151C"},"contest":{"kind":"string","value":"151"},"problem":{"kind":"string","value":"C"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"C. Win or Freeze"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Win or Freeze</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You can't possibly imagine how cold our friends are this winter in Nvodsk! Two of them play the following game to warm up: initially a piece of paper has an integer <span class=\"tex-span\"><i>q</i></span>. During a move a player should write any integer number that is a <span class=\"tex-font-style-underline\">non-trivial</span> divisor of the last written number. Then he should run this number of circles around the hotel. Let us remind you that a number's divisor is called <span class=\"tex-font-style-underline\">non-trivial</span> if it is different from one and from the divided number itself. </p><p>The first person who <span class=\"tex-font-style-bf\">can't make a move wins</span> as he continues to lie in his warm bed under three blankets while the other one keeps running. Determine which player wins considering that both players play optimally. If the first player wins, print any winning first move.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the only integer <span class=\"tex-span\"><i>q</i></span> (<span class=\"tex-span\">1 ≤ <i>q</i> ≤ 10<sup class=\"upper-index\">13</sup></span>).</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the number of the winning player (<span class=\"tex-span\">1</span> or <span class=\"tex-span\">2</span>). If the first player wins then the second line should contain another integer — his first move (if the first player can't even make the first move, print <span class=\"tex-span\">0</span>). If there are multiple solutions, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>6<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>30<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/>6<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/>0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Number <span class=\"tex-span\">6</span> has only two non-trivial divisors: <span class=\"tex-span\">2</span> and <span class=\"tex-span\">3</span>. It is impossible to make a move after the numbers <span class=\"tex-span\">2</span> and <span class=\"tex-span\">3</span> are written, so both of them are winning, thus, number <span class=\"tex-span\">6</span> is the losing number. A player can make a move and write number <span class=\"tex-span\">6</span> after number <span class=\"tex-span\">30</span>; <span class=\"tex-span\">6</span>, as we know, is a losing number. 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Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='8735f4dd087d2d2e6d5a85f0696aa6b8'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/151/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = $(this).hasClass(\"la-angle-right\");\r\n const params = {\r\n action: \"setCollapsed\",\r\n sidebarFrameSimpleClassName: \"ContestVirtualFrame\",\r\n collapsed\r\n };\r\n $.each($target[0].attributes, function(i, a) {\r\n const name = a.name;\r\n if (name.startsWith(\"data-extra-key-\")) {\r\n const key = a.value;\r\n const keyIndex = parseInt(name.substring(\"data-extra-key-\".length));\r\n const value = $target.attr(\"data-extra-value-\" + keyIndex);\r\n params[key] = value;\r\n }\r\n });\r\n $.post(dataPageUrl, params, function (result) {\r\n if (result[\"success\"] !== \"true\") {\r\n Codeforces.showMessage(\"Failed to save collapsed state.\");\r\n }\r\n }, \"json\");\r\n return false;\r\n });\r\n })\r\n </script>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Problem tags\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\"padding: 0.5em;\">\r\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Games, Sprague–Grundy theorem\">\r\n games\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Greedy algorithms\">\r\n greedy\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Mathematics including integration, differential equations, etc\">\r\n math\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Number theory: Euler function, GCD, divisibility, etc\">\r\n number theory\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *1400\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='8735f4dd087d2d2e6d5a85f0696aa6b8'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"936\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='8735f4dd087d2d2e6d5a85f0696aa6b8'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"936\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3899\" title=\"Codeforces Round #107\" target=\"_blank\">Codeforces Round #107</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"365:366\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3905\" title=\"Codeforces Round #107. Tutorial.\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"946:947\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/151\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/151/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/151/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/151/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/151/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/151/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/151/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/151/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const nodeToText = function (node, pre) {\r\n let result = [];\r\n\r\n if (node.tagName === \"SCRIPT\" || node.tagName === \"math\"\r\n || (node.classList && node.classList.contains(\"input-output-copier\")))\r\n return [];\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(OPENING_SPACE);\r\n }\r\n\r\n if (node.nodeType === Node.TEXT_NODE) {\r\n let s = node.textContent;\r\n if (!pre) {\r\n s = s.replace(/\\s+/g, \" \");\r\n }\r\n if (s.length > 0) {\r\n result.push(s);\r\n }\r\n }\r\n\r\n if (pre && node.tagName === \"BR\") {\r\n result.push(\"\\n\");\r\n }\r\n\r\n node.childNodes.forEach(function (child) {\r\n result.push(nodeToText(child, node.tagName === \"PRE\").join(\"\"));\r\n });\r\n\r\n if (node.tagName === \"DIV\"\r\n || node.tagName === \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_2291263f7707e90248e498c403ec8b8f9c3f5fc6\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Win or Freeze</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You can't possibly imagine how cold our friends are this winter in Nvodsk! Two of them play the following game to warm up: initially a piece of paper has an integer <span class=\"tex-span\"><i>q</i></span>. During a move a player should write any integer number that is a <span class=\"tex-font-style-underline\">non-trivial</span> divisor of the last written number. Then he should run this number of circles around the hotel. Let us remind you that a number's divisor is called <span class=\"tex-font-style-underline\">non-trivial</span> if it is different from one and from the divided number itself. </p><p>The first person who <span class=\"tex-font-style-bf\">can't make a move wins</span> as he continues to lie in his warm bed under three blankets while the other one keeps running. Determine which player wins considering that both players play optimally. If the first player wins, print any winning first move.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the only integer <span class=\"tex-span\"><i>q</i></span> (<span class=\"tex-span\">1 ≤ <i>q</i> ≤ 10<sup class=\"upper-index\">13</sup></span>).</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the number of the winning player (<span class=\"tex-span\">1</span> or <span class=\"tex-span\">2</span>). If the first player wins then the second line should contain another integer — his first move (if the first player can't even make the first move, print <span class=\"tex-span\">0</span>). If there are multiple solutions, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>6<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>30<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br />6<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br />0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Number <span class=\"tex-span\">6</span> has only two non-trivial divisors: <span class=\"tex-span\">2</span> and <span class=\"tex-span\">3</span>. It is impossible to make a move after the numbers <span class=\"tex-span\">2</span> and <span class=\"tex-span\">3</span> are written, so both of them are winning, thus, number <span class=\"tex-span\">6</span> is the losing number. A player can make a move and write number <span class=\"tex-span\">6</span> after number <span class=\"tex-span\">30</span>; <span class=\"tex-span\">6</span>, as we know, is a losing number. Thus, this move will bring us the victory.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=C]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n $problem.find(\"a.view-changes\").click(function() {\r\n $.post(\"/data/diff\", {action: \"getDiff\", a: previousStatementText, b: statementText}, function (result) {\r\n if (result[\"success\"] === \"true\") {\r\n Codeforces.facebox(\".diff-popup\", 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:19</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='7e06e3404f9e0c1af534082ddbd4b3d4'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":751,"cells":{"problem_id":{"kind":"string","value":"151D"},"contest":{"kind":"string","value":"151"},"problem":{"kind":"string","value":"D"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"D. Quantity of Strings"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Quantity of Strings</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Just in case somebody missed it: this winter is totally cold in Nvodsk! It is so cold that one gets funny thoughts. For example, let's say there are strings with the length exactly <span class=\"tex-span\"><i>n</i></span>, based on the alphabet of size <span class=\"tex-span\"><i>m</i></span>. Any its substring with length equal to <span class=\"tex-span\"><i>k</i></span> is a palindrome. How many such strings exist? Your task is to find their quantity modulo <span class=\"tex-span\">1000000007</span> (<span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>). Be careful and don't miss a string or two!</p><p>Let us remind you that a string is a palindrome if it can be read the same way in either direction, from the left to the right and from the right to the left.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first and only line contains three integers: <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i>, <i>k</i> ≤ 2000</span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single integer — the number of strings of the described type modulo <span class=\"tex-span\">1000000007</span> (<span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>).</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 2 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample only one string is valid: \"<span class=\"tex-font-style-tt\">a</span>\" (let's denote the only letter of our alphabet as \"<span class=\"tex-font-style-tt\">a</span>\").</p><p>In the second sample (if we denote the alphabet letters as \"<span class=\"tex-font-style-tt\">a</span>\" and \"<span class=\"tex-font-style-tt\">b</span>\") the following strings are valid: \"<span class=\"tex-font-style-tt\">aaaaa</span>\" and \"<span class=\"tex-font-style-tt\">bbbbb</span>\".</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"8921fc87cb1842514264fd585c5f7c81\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"ea8e0bdb7b51062f470d1988db24be37dd2a76af\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='8921fc87cb1842514264fd585c5f7c81'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/151/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = $(this).hasClass(\"la-angle-right\");\r\n const params = {\r\n action: \"setCollapsed\",\r\n sidebarFrameSimpleClassName: \"ContestVirtualFrame\",\r\n collapsed\r\n };\r\n $.each($target[0].attributes, function(i, a) {\r\n const name = a.name;\r\n if (name.startsWith(\"data-extra-key-\")) {\r\n const key = a.value;\r\n const keyIndex = parseInt(name.substring(\"data-extra-key-\".length));\r\n const value = $target.attr(\"data-extra-value-\" + keyIndex);\r\n params[key] = value;\r\n }\r\n });\r\n $.post(dataPageUrl, params, function (result) {\r\n if (result[\"success\"] !== \"true\") {\r\n Codeforces.showMessage(\"Failed to save collapsed state.\");\r\n }\r\n }, \"json\");\r\n return false;\r\n });\r\n })\r\n </script>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Problem tags\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\"padding: 0.5em;\">\r\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Combinatorics\">\r\n combinatorics\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Disjoint set union\">\r\n dsu\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Graphs\">\r\n graphs\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Mathematics including integration, differential equations, etc\">\r\n math\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *1600\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='8921fc87cb1842514264fd585c5f7c81'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"937\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='8921fc87cb1842514264fd585c5f7c81'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"937\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3899\" title=\"Codeforces Round #107\" target=\"_blank\">Codeforces Round #107</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"365:366\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3905\" title=\"Codeforces Round #107. Tutorial.\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"946:947\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/151\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/151/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/151/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/151/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/151/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/151/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/151/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/151/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const nodeToText = function (node, pre) {\r\n let result = [];\r\n\r\n if (node.tagName === \"SCRIPT\" || node.tagName === \"math\"\r\n || (node.classList && node.classList.contains(\"input-output-copier\")))\r\n return [];\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(OPENING_SPACE);\r\n }\r\n\r\n if (node.nodeType === Node.TEXT_NODE) {\r\n let s = node.textContent;\r\n if (!pre) {\r\n s = s.replace(/\\s+/g, \" \");\r\n }\r\n if (s.length > 0) {\r\n result.push(s);\r\n }\r\n }\r\n\r\n if (pre && node.tagName === \"BR\") {\r\n result.push(\"\\n\");\r\n }\r\n\r\n node.childNodes.forEach(function (child) {\r\n result.push(nodeToText(child, node.tagName === \"PRE\").join(\"\"));\r\n });\r\n\r\n if (node.tagName === \"DIV\"\r\n || node.tagName === \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_209dd2b7d74aa226f17f9a83b87bf22f9e9c71a5\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Quantity of Strings</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Just in case somebody missed it: this winter is totally cold in Nvodsk! It is so cold that one gets funny thoughts. For example, let's say there are strings with the length exactly <span class=\"tex-span\"><i>n</i></span>, based on the alphabet of size <span class=\"tex-span\"><i>m</i></span>. Any its substring with length equal to <span class=\"tex-span\"><i>k</i></span> is a palindrome. How many such strings exist? Your task is to find their quantity modulo <span class=\"tex-span\">1000000007</span> (<span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>). Be careful and don't miss a string or two!</p><p>Let us remind you that a string is a palindrome if it can be read the same way in either direction, from the left to the right and from the right to the left.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first and only line contains three integers: <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i>, <i>k</i> ≤ 2000</span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single integer — the number of strings of the described type modulo <span class=\"tex-span\">1000000007</span> (<span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>).</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 2 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample only one string is valid: "<span class=\"tex-font-style-tt\">a</span>" (let's denote the only letter of our alphabet as "<span class=\"tex-font-style-tt\">a</span>").</p><p>In the second sample (if we denote the alphabet letters as "<span class=\"tex-font-style-tt\">a</span>" and "<span class=\"tex-font-style-tt\">b</span>") the following strings are valid: "<span class=\"tex-font-style-tt\">aaaaa</span>" and "<span class=\"tex-font-style-tt\">bbbbb</span>".</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=D]\");\r\n let uuid = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:19</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='7e06e3404f9e0c1af534082ddbd4b3d4'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":752,"cells":{"problem_id":{"kind":"string","value":"151E"},"contest":{"kind":"string","value":"151"},"problem":{"kind":"string","value":"E"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"E. Smart Cheater"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Smart Cheater</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>I guess there's not much point in reminding you that Nvodsk winters aren't exactly hot. That increased the popularity of the public transport dramatically. The route of bus <span class=\"tex-span\">62</span> has exactly <span class=\"tex-span\"><i>n</i></span> stops (stop <span class=\"tex-span\">1</span> goes first on its way and stop <span class=\"tex-span\"><i>n</i></span> goes last). The stops are positioned on a straight line and their coordinates are <span class=\"tex-span\">0 = <i>x</i><sub class=\"lower-index\">1</sub> < <i>x</i><sub class=\"lower-index\">2</sub> < ... < <i>x</i><sub class=\"lower-index\"><i>n</i></sub></span>. </p><p>Each day exactly <span class=\"tex-span\"><i>m</i></span> people use bus <span class=\"tex-span\">62</span>. For each person we know the number of the stop where he gets on the bus and the number of the stop where he gets off the bus. A ticket from stop <span class=\"tex-span\"><i>a</i></span> to stop <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>a</i> < <i>b</i></span>) costs <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>b</i></sub> - <i>x</i><sub class=\"lower-index\"><i>a</i></sub></span> rubles. However, the conductor can choose no more than one segment NOT TO SELL a ticket for. We mean that conductor should choose C and D (С <= D) and sell a ticket for the segments [<span class=\"tex-span\"><i>A</i></span>, <span class=\"tex-span\"><i>C</i></span>] and [<span class=\"tex-span\"><i>D</i></span>, <span class=\"tex-span\"><i>B</i></span>], or not sell the ticket at all. The conductor and the passenger divide the saved money between themselves equally. The conductor's \"untaxed income\" is sometimes interrupted by inspections that take place as the bus drives on some segment of the route located between two consecutive stops. The inspector fines the conductor by <span class=\"tex-span\"><i>c</i></span> rubles for each passenger who doesn't have the ticket for this route's segment.</p><p>You know the coordinated of all stops <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>; the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>); the fine <span class=\"tex-span\"><i>c</i></span>; and also <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> — the probability of inspection on segment between the <span class=\"tex-span\"><i>i</i></span>-th and the <span class=\"tex-span\"><i>i</i> + 1</span>-th stop. The conductor asked you to help him make a plan of selling tickets that maximizes the mathematical expectation of his profit.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>c</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 150 000</span>, <span class=\"tex-span\">1 ≤ <i>m</i> ≤ 300 000</span>, <span class=\"tex-span\">1 ≤ <i>c</i> ≤ 10 000</span>).</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> = 0</span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub> < <i>x</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>) — the coordinates of the stops on the bus's route.</p><p>The third line contains <span class=\"tex-span\"><i>n</i> - 1</span> integer <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the probability of inspection in percents on the segment between stop <span class=\"tex-span\"><i>i</i></span> and stop <span class=\"tex-span\"><i>i</i> + 1</span>.</p><p>Then follow <span class=\"tex-span\"><i>m</i></span> lines that describe the bus's passengers. Each line contains exactly two integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>) — the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the maximum expectation of the conductor's profit. Your answer will be considered correct if its absolute or relative error does not exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 6</sup></span>. </p><p>Namely: let's assume that your answer is <span class=\"tex-span\"><i>a</i></span>, and the answer of the jury is <span class=\"tex-span\"><i>b</i></span>. The checker program will consider your answer correct, if <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/c97ba2000ebfad962bff7ffd8d043594f5ae1086.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 10<br/>0 10 100<br/>100 0<br/>1 2<br/>2 3<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>90.000000000<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 8 187<br/>0 10 30 70 150 310 630 1270 2550 51100<br/>13 87 65 0 100 44 67 3 4<br/>1 10<br/>2 9<br/>3 8<br/>1 5<br/>6 10<br/>2 7<br/>4 10<br/>4 5<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>76859.990000000<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample:</p><p>The first and third passengers get tickets from stop <span class=\"tex-span\">1</span> to stop <span class=\"tex-span\">2</span>. The second passenger doesn't get a ticket. There always is inspection on the segment <span class=\"tex-span\">1</span>-<span class=\"tex-span\">2</span> but both passengers have the ticket for it. There never is an inspection on the segment <span class=\"tex-span\">2</span>-<span class=\"tex-span\">3</span>, that's why the second passenger gets away with the cheating. Our total profit is <span class=\"tex-span\">(0 + 90 / 2 + 90 / 2) = 90</span>.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"6916f36522e04eb5d89e4adb44bdc32f\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"ea8e0bdb7b51062f470d1988db24be37dd2a76af\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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Smart Cheater</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>I guess there's not much point in reminding you that Nvodsk winters aren't exactly hot. That increased the popularity of the public transport dramatically. The route of bus <span class=\"tex-span\">62</span> has exactly <span class=\"tex-span\"><i>n</i></span> stops (stop <span class=\"tex-span\">1</span> goes first on its way and stop <span class=\"tex-span\"><i>n</i></span> goes last). The stops are positioned on a straight line and their coordinates are <span class=\"tex-span\">0 = <i>x</i><sub class=\"lower-index\">1</sub> < <i>x</i><sub class=\"lower-index\">2</sub> < ... < <i>x</i><sub class=\"lower-index\"><i>n</i></sub></span>. </p><p>Each day exactly <span class=\"tex-span\"><i>m</i></span> people use bus <span class=\"tex-span\">62</span>. For each person we know the number of the stop where he gets on the bus and the number of the stop where he gets off the bus. A ticket from stop <span class=\"tex-span\"><i>a</i></span> to stop <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>a</i> < <i>b</i></span>) costs <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>b</i></sub> - <i>x</i><sub class=\"lower-index\"><i>a</i></sub></span> rubles. However, the conductor can choose no more than one segment NOT TO SELL a ticket for. We mean that conductor should choose C and D (С <= D) and sell a ticket for the segments [<span class=\"tex-span\"><i>A</i></span>, <span class=\"tex-span\"><i>C</i></span>] and [<span class=\"tex-span\"><i>D</i></span>, <span class=\"tex-span\"><i>B</i></span>], or not sell the ticket at all. The conductor and the passenger divide the saved money between themselves equally. The conductor's "untaxed income" is sometimes interrupted by inspections that take place as the bus drives on some segment of the route located between two consecutive stops. The inspector fines the conductor by <span class=\"tex-span\"><i>c</i></span> rubles for each passenger who doesn't have the ticket for this route's segment.</p><p>You know the coordinated of all stops <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>; the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>); the fine <span class=\"tex-span\"><i>c</i></span>; and also <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> — the probability of inspection on segment between the <span class=\"tex-span\"><i>i</i></span>-th and the <span class=\"tex-span\"><i>i</i> + 1</span>-th stop. The conductor asked you to help him make a plan of selling tickets that maximizes the mathematical expectation of his profit.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>c</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 150 000</span>, <span class=\"tex-span\">1 ≤ <i>m</i> ≤ 300 000</span>, <span class=\"tex-span\">1 ≤ <i>c</i> ≤ 10 000</span>).</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> = 0</span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub> < <i>x</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>) — the coordinates of the stops on the bus's route.</p><p>The third line contains <span class=\"tex-span\"><i>n</i> - 1</span> integer <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the probability of inspection in percents on the segment between stop <span class=\"tex-span\"><i>i</i></span> and stop <span class=\"tex-span\"><i>i</i> + 1</span>.</p><p>Then follow <span class=\"tex-span\"><i>m</i></span> lines that describe the bus's passengers. Each line contains exactly two integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> < <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>) — the numbers of stops where the <span class=\"tex-span\"><i>i</i></span>-th passenger gets on and off.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the maximum expectation of the conductor's profit. Your answer will be considered correct if its absolute or relative error does not exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 6</sup></span>. </p><p>Namely: let's assume that your answer is <span class=\"tex-span\"><i>a</i></span>, and the answer of the jury is <span class=\"tex-span\"><i>b</i></span>. The checker program will consider your answer correct, if <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/c97ba2000ebfad962bff7ffd8d043594f5ae1086.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" />.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 10<br />0 10 100<br />100 0<br />1 2<br />2 3<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>90.000000000<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 8 187<br />0 10 30 70 150 310 630 1270 2550 51100<br />13 87 65 0 100 44 67 3 4<br />1 10<br />2 9<br />3 8<br />1 5<br />6 10<br />2 7<br />4 10<br />4 5<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>76859.990000000<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>A comment to the first sample:</p><p>The first and third passengers get tickets from stop <span class=\"tex-span\">1</span> to stop <span class=\"tex-span\">2</span>. The second passenger doesn't get a ticket. There always is inspection on the segment <span class=\"tex-span\">1</span>-<span class=\"tex-span\">2</span> but both passengers have the ticket for it. There never is an inspection on the segment <span class=\"tex-span\">2</span>-<span class=\"tex-span\">3</span>, that's why the second passenger gets away with the cheating. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:19</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='7e06e3404f9e0c1af534082ddbd4b3d4'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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href=\"/profile/SergeiFedorov\">SergeiFedorov</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/SergeiFedorov\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/SergeiFedorov\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/SergeiFedorov\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/SergeiFedorov\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/SergeiFedorov\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/SergeiFedorov\" style=\"text-decoration:none;color:black !important;\">SergeiFedorov's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3919\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3905\"> <p>Codeforces Round #107. Tutorial.</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/SergeiFedorov\" title=\"Grandmaster SergeiFedorov\" class=\"rated-user user-red\">SergeiFedorov</a>,\r\n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h3><a href=\"/contest/150/problem/E\" title=\"Codeforces Round 107 (Div. 1)\">150E - Freezing with Style</a></h3> <ol> <li><p>If there exists a path with the median <span class=\"tex-span\"> ≥ <i>k</i></span>, for some <span class=\"tex-span\"><i>k</i></span>, then there exists a path with the median <span class=\"tex-span\"> ≥ <i>q</i></span>, for each <span class=\"tex-span\"><i>q</i> ≤ <i>k</i></span>. That means we can use binary search to calculate the answer. So now the task is: is there any path with the median greater or equal to <span class=\"tex-span\"><i>Mid</i></span> ?</p></li> <li><p>We will calc the edge as <span class=\"tex-span\"> + 1</span> if it's wight <span class=\"tex-span\"> ≥ <i>Mid</i></span>, or as <span class=\"tex-span\"> - 1</span> in other case. Now we only need to check if there exists a path with legal length and the sum greater than or equal to zero.</p></li> <li><p>Let's denote some node <span class=\"tex-span\"><i>V</i></span> as a root.</p></li> <li><p>All paths can be divided into two types: that contains <span class=\"tex-span\"><i>v</i></span>, and that do not. Now we are to process all first-type paths and run the algorithm on all subtrees. That is so-called divide-and-conquer strategy.</p></li> <li><p>We can trivially show that it is always possible to choose such vertex <span class=\"tex-span\"><i>v</i></span> that all it's subtrees will have size less than or equal to the size of the whole tree. That means that each node will be proccessed in <span class=\"tex-span\"><i>LogN</i></span> trees max.</p></li> <li><p>So, if we solve the task for one level of recursion in <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>))</span>, we'll solve it in time <span class=\"tex-span\"><i>O</i>(<i>F</i>(<i>N</i>) * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> on the whole.</p></li> <li><p>First, lets get <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>Log</i>(<i>N</i>))</span>. For each node we shall calc it's deepness, cost of the path to the root ans the first edge (the number of the root's subtree). It will be better now to use 2 and 0 as the edges costs, instead of -1 and 1. Now we shall process root's subtrees one by one. For each node we want to know if there exists a node <span class=\"tex-span\"><i>u</i></span> in any other subtree such that the </p><p>Unable to parse markup [type=CF_TEX]</p> and <span class=\"tex-span\"><i>cost</i>[<i>v</i>] - <i>deep</i>[<i>v</i>] + <i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>] ≥ 0</span>. To do that we need to know the maximum of the function <span class=\"tex-span\">(<i>cost</i>[<i>u</i>] - <i>deep</i>[<i>u</i>])</span> with the deep values between max(0, <span class=\"tex-span\"><i>L</i> - <i>deep</i>[<i>v</i>]</span>) and <span class=\"tex-span\"><i>R</i> - <i>deep</i>[<i>v</i>]</span> inclusive. To achieve <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i>(<i>N</i>))</span> you need only to use segment tree.</li> <li><p>To achieve an AC contestants were to write all code optimally, or to think of one more idea. It is possible to have <span class=\"tex-span\"><i>O</i>(<i>N</i>)</span> on one level of recursion and <span class=\"tex-span\"><i>O</i>(<i>N</i> * <i>log</i><sup class=\"upper-index\">2</sup>(<i>N</i>))</span> in total if you sort roots subtrees in non-decreasing order and use any structure that can answer getmax query on all segments of length <span class=\"tex-span\">(<i>R</i> - <i>L</i> + 1)</span> and all prefixes and suffixes.</p></li> </ol><p>Best of luck to you in upsolving this problem!</p><h3><a href=\"/contest/150/problem/D\" title=\"Codeforces Round 107 (Div. 1)\">150D - Mission Impassable</a></h3><p>In this problem you have to use dynamic programming. For our convenience we will calulate three type of values:</p><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span>.</p><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> if he fully destroys it.</p><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>Len</i>]</span> — best result player can achieve on the segment from <span class=\"tex-span\">[<i>l</i>, <i>r</i>]</span> and remain the palindrome of length <span class=\"tex-span\"><i>len</i></span> and only it.</p><p>Now solution:</p> <ol> <li><p><span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>r</i>]</span>. Let's look which move will be the last. This will be removing the palindrome of length <span class=\"tex-span\"><i>len</i></span> and <span class=\"tex-span\"><i>c</i>[<i>len</i>] ≥ 0</span>. What is the best result we can achieve? <span class=\"tex-span\"><i>c</i>[<i>len</i>] + <i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>.</p></li> <li><p><span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span>. Either we will destroy all subtring from <span class=\"tex-span\"><i>l</i></span> to <span class=\"tex-span\"><i>r</i></span>, either there exists a letter which we did not touch. That means that all our moves lies fully to the left or fully to the rigth to that position. So <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>] = <i>Full</i>[<i>l</i>][<i>r</i>]</span> or <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>r</i>]</span> = <span class=\"tex-span\"><i>Best</i>[<i>l</i>][<i>m</i>] + <i>Best</i>[<i>m</i> + 1][<i>r</i>]</span> for some <span class=\"tex-span\"><i>m</i></span>, <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>.</p></li> <li><p><span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>r</i>][<i>len</i>]</span>. <span class=\"tex-span\"><i>len</i> = 0</span>, <span class=\"tex-span\"><i>len</i> = 1</span> — two special cases, which is easy to solve without any dynamic. In other case, let's take a look on the left-most position. It either will lie in the result string or not. If not, then let's find the first position which does. Denote it as <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Everything what lies to the left need to be fully deleted. So the answer is <span class=\"tex-span\"><i>Full</i>[<i>l</i>][<i>m</i> - 1] + <i>T</i>[<i>m</i>][<i>r</i>][<i>len</i>]</span> (for <span class=\"tex-span\"><i>l</i> < <i>m</i> ≤ <i>r</i></span>). Similarly, for the right-most letters. If it does not lies in the result string we remove everything to the right and our result is <span class=\"tex-span\"><i>T</i>[<i>l</i>][<i>m</i>][<i>len</i>] + <i>Full</i>[<i>m</i> + 1][<i>r</i>]</span> (for <span class=\"tex-span\"><i>l</i> ≤ <i>m</i> < <i>r</i></span>). The last option: both left-most and rigth-most letters lies in the result string. It is possible only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = <i>s</i>[<i>r</i>]</span>. So our result is <span class=\"tex-span\"><i>T</i>[<i>l</i> + 1][<i>r</i> - 1][<i>len</i> - 2]</span> (only if <span class=\"tex-span\"><i>s</i>[<i>l</i>] = = <i>s</i>[<i>r</i>]</span>).</p></li> </ol><h3><a href=\"/contest/150/problem/C\" title=\"Codeforces Round 107 (Div. 1)\">150C - Smart Cheater</a></h3> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> <li><p>Now we only need to find the subsegment of segment [a, b] of maximal sum for each passanger.</p></li> <li><p>That's easy to do by the segment tree, we only need to calc four values for each node:</p></li> </ol><p>best — the maximal sum of elements on some subsegment</p><p>max_left — the maximal sum on prefix</p><p>max_right — the maximal sum on suffix</p><p>sum — the sum of all elements</p><h3><a href=\"/contest/150/problem/B\" title=\"Codeforces Round 107 (Div. 1)\">150B - Quantity of Strings</a></h3><p>We can offer you two solitions:</p> <ol> <li><p>You can build a graph with positions in sting as a nodes and equality in any substring of length <span class=\"tex-span\"><i>k</i></span> as edges. Lets denote <span class=\"tex-span\"><i>e</i></span> the number of components in the graph. The answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>e</i></sup></span>.</p></li> <li><p>Analyze four cases: </p> <ul> <li><span class=\"tex-span\"><i>k</i> = 1</span> or <span class=\"tex-span\"><i>к</i> > <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</li> <li><span class=\"tex-span\"><i>k</i> = <i>n</i></span>, the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">(<i>n</i> + 1) / 2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 1</span>, any string like abababab... is ok, so the answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\">2</sup></span>.</li> <li><span class=\"tex-span\"><i>k</i></span> mod <span class=\"tex-span\">2 = 0</span>, all symbols coincide and the answer is <span class=\"tex-span\"><i>m</i></span>.</li> </ul></li> </ol><h3><a href=\"/contest/150/problem/A\" title=\"Codeforces Round 107 (Div. 1)\">150A - Win or Freeze</a></h3> <ul> <li><p>if <span class=\"tex-span\"><i>Q</i></span> is prime or <span class=\"tex-span\"><i>Q</i> = 1</span> than it's victory.</p></li> <li><p>We loose if: <span class=\"tex-span\"><i>Q</i> = <i>p</i> * <i>q</i></span> or <span class=\"tex-span\"><i>Q</i> = <i>p</i><sup class=\"upper-index\">2</sup></span>, where <span class=\"tex-span\"><i>p</i></span> and <span class=\"tex-span\"><i>q</i></span> are prime.</p></li> <li><p>It is quite obvious that it is always possible to move in bad position in any other case. That means all other numbers grants us the victory.</p></li> </ul><p>We only have to check if <span class=\"tex-span\"><i>Q</i></span> has a divisor of the loose type. We can easily do it in <span class=\"tex-span\"><i>O</i>(<i>sqrt</i>(<i>Q</i>))</span> time.</p><h3><a href=\"/contest/151/problem/B\" title=\"Codeforces Round 107 (Div. 2)\">151B - Phone Numbers</a></h3><p>In this task you were to implement the described selection of the maximum elements.</p><h3><a href=\"/contest/151/problem/A\" title=\"Codeforces Round 107 (Div. 2)\">151A - Soft Drinking</a></h3><p>Soda will be enough for <span class=\"tex-span\"><i>gas</i></span> = <span class=\"tex-span\">(<i>K</i></span> * <span class=\"tex-span\"><i>L</i>)</span> / <span class=\"tex-span\">(<i>N</i></span> * <span class=\"tex-span\"><i>l</i>)</span> toasts.</p><p>Limes will last for <span class=\"tex-span\"><i>laim</i> = (<i>C</i> * <i>D</i>) / <i>N</i></span> toasts.</p><p>Salt is enough for <span class=\"tex-span\"><i>sol</i> = <i>P</i> / (<i>p</i> * <i>N</i>)</span> toasts.</p><p>Total result: <span class=\"tex-span\"><i>res</i> = <i>min</i>(<i>gas</i>, <i>laim</i>, <i>sol</i>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/151\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 107 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-527-3919\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"527\",\n blogEntryId: \"3905\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=tutorial\" class=\"tag notice\" style=\"text-decoration: none;\">tutorial</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=cf+107\" class=\"tag notice\" style=\"text-decoration: none;\">cf 107</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+68</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3919\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/SergeiFedorov\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/SergeiFedorov\">\n SergeiFedorov\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/17/2012 21:33\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3905#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3905#comments\">\n 25\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3929\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (19)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79388\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/luyi0619\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/11675/avatar/609fd9c977112b88.jpg'/> </a>\n <div><a href=\"/profile/luyi0619\" title=\"Expert luyi0619\" class=\"rated-user user-blue\">luyi0619</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 15:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79388\" href=\"?#comment-79388\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79388\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79388\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"11675\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79388\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>For 150B, i think if you give a "k > n case" in the sample , it will reduce lots of misunderstanding.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79388 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79388 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79388\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79390\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:18\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79390\" href=\"?#comment-79390\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79390\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79390\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone give a more detailed explanation for 150B in the cases when k%2=0 and k%2=1.Its not clear for me</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79390 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79390 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79390\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79396\" commentParentId=\"79390\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:37\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79396\" href=\"?#comment-79396\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79390\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79396\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79396\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Before we check whether k is odd or even(k%2 == 1 or k%2 == 0), we check following two conditions.</p><p>k = 1 or к > n, the answer is mn. k = n, the answer is m(n + 1) / 2.</p><p>So we know the current k is 0 < k < n</p><p>Let's look at the case when k%2 == 1 Let a = an arbitrary character from "m" possible characters. b = an arbitrary character other than "a" from "m" possible characters</p><p>If k is odd, a substring whose length is k out of following string is always a palindrome. String : abababababa Substring k=3 => aba or bab k=5 => ababa or babab ... you see the pattern. So we have (m * (m-1)) possible patterns. Now, also remember that a string consisting of same characters are also allowed. string : aaaaaaa substring k=3 =>aaa k=5 => aaaaa And we have "m" number of such strings.</p><p>So answer is m*(m-1) + m = m*(m-1+1) = m*m</p><p>Let's see what happens when k is even. If k is even, only allowed strings are the ones that consist of same characters. There are m such strings. So answer for (k%2 == 0) is m </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79396 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79396 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79396\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79428\" commentParentId=\"79396\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/phantom11\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/23523/avatar/db14eeb7ddf66e49.jpg'/> </a>\n <div><a href=\"/profile/phantom11\" title=\"Expert phantom11\" class=\"rated-user user-blue\">phantom11</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 18:10\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79428\" href=\"?#comment-79428\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79396\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79428\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"23523\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79428\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for the explanation :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79428 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79428 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79428\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79392\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:29\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79392\" href=\"?#comment-79392\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79392\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-9\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79392\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I actually failed 150B because of case k > n, and I still don't understand why it is regard the same as k == 1.</p><p>case where k == 1 is trivial. The answer is all possible strings.</p><p>However, in case k > n, I think the answer should be 0 because you cannot make a SUBSTRING whose length is LONGER than the ORIGINAL string. Also, by definition, a substring is a part of a string, not extended version of a string.</p><p>Let's take an example. Let's say n == 5 and k == 7. You have strings made out of "m" selection of characters, and the strings' lengths are always 5. How can you possibly make a substring whose length is 7 from one of strings whose length is 5?</p><p>If I am wrong, please help me understand why all possible strings are regarded as palindrome when k > n.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79392 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79392 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79392\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79394\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:32\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79394\" href=\"?#comment-79394\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79394\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79394\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>All 0 k-substrings of any string is palindromes.</p><p>So any string is correct.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79394 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79394 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79394\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79397\" commentParentId=\"79394\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79397\" href=\"?#comment-79397\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79394\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79397\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79397\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>What do you mean by "0 k-substrings of any stirng" ?</p><p>Could you please explain with a litte bit more detail?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79397 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79397 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79397\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79399\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/riadwaw\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/8452/avatar/7b374574b05a50df.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/riadwaw\" title=\"International Master riadwaw\" class=\"rated-user user-orange\">riadwaw</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79399\" href=\"?#comment-79399\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79399\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"10\"\r\n data-commentUserId=\"8452\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+10</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79399\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There are 0 substrings of length <code>k</code>.<br />All of them are palindromes because Any statement about empty set is truth</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79399 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79399 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79399\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79404\" commentParentId=\"79399\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/TurtleShip\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/32220/avatar/232c80a0a3b3e706.jpg'/> </a>\n <div><a href=\"/profile/TurtleShip\" title=\"Expert TurtleShip\" class=\"rated-user user-blue\">TurtleShip</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79404\" href=\"?#comment-79404\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79399\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79404\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"32220\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79404\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thx.I get it now. :-)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79404 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79404 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79404\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79401\" commentParentId=\"79397\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Hohol\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/198/avatar/9feafb975d9089d3.jpg'/> </a>\n <div><a href=\"/profile/Hohol\" title=\"Candidate Master Hohol\" class=\"rated-user user-violet\">Hohol</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:43\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79401\" href=\"?#comment-79401\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79397\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79401\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"16\"\r\n data-commentUserId=\"198\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+16</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79401\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://en.wikipedia.org/wiki/Vacuous_truth\">http://en.wikipedia.org/wiki/Vacuous_truth</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79401 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79401 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79401\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79405\" commentParentId=\"79392\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Zlobober\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4808/avatar/5d51bfacd488a780.jpg'/> </a>\n <div><a href=\"/profile/Zlobober\" title=\"International Grandmaster Zlobober\" class=\"rated-user user-red\">Zlobober</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/19/2012 16:49\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79405\" href=\"?#comment-79405\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79392\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79405\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"4808\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79405\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Let's solve your example (n = 5, k = 7) step by step. Let's check every possible string (let m be 2) if it satisfies the condition. </p><p>Let's look on string abaab. Condition is that every substring of length 7 of string abaab is palindrome. Set of such substrings S is empty, it's obvious. So the condition "every element x of S is palindrome" is true.</p><p>If you still don't believe me, let's look another way. If condition of type "every element a in set B satisfies condition C" is false, that means, that exists some element <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/88a42d24f09eb9564ade0a1b1972f6708dbffa74.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> that don't satisfy condition C. In out example, if string abaab doesn't satisfy our condition, then there exist some substring x of our string, that x isn't palindrome. But you can't choose such x: there is no substring of length 7 in our string. So the proposition of that abaab doesn't satisfy condition is false. So this condition is true for abaab, so we have to include abaab to answer.</p><p>Such proof is correct for every string of length n on m-alhpabet, so answer is <span class=\"tex-span\"><i>m</i><sup class=\"upper-index\"><i>n</i></sup></span>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79405 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79405 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79405\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79571\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nsun48\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/nsun48\" title=\"Candidate Master nsun48\" class=\"rated-user user-violet\">nsun48</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/20/2012 18:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79571\" href=\"?#comment-79571\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79571\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79571\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"39914\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79571\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>i like these problems, but that editorial for 151B is sort of ...</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79571 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79571 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79571\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"188218\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mckkentmwk\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/mckkentmwk\" title=\"Expert mckkentmwk\" class=\"rated-user user-blue\">mckkentmwk</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/19/2014 21:28\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-188218\" href=\"?#comment-188218\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"188218\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"58170\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-188218\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Hi everyone. For 150C can anyone explain details of the point 1 and 2 of this problem?</p> <ol> <li><p>First lets use the linearity of expected value and solve task independently for each passanger.</p></li> <li><p>For each path segment (route between neighboring stations) we calculate expected value of profit in case we do not sell a ticket for this segment. In case we sell it the expectation of profit is 0.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-188218 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-188218 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-188218\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"385265\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/yaksha\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/595919/avatar/35f0d64f1f410b9c.jpg'/> </a>\n <div><a href=\"/profile/yaksha\" title=\"Candidate Master yaksha\" class=\"rated-user user-violet\">yaksha</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/13/2017 19:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-385265\" href=\"?#comment-385265\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"385265\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"595919\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-385265\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone help me out with the graph approach of problem 150B, the other approach is straight forward but I can't wrap my head around the graph one, thanks!!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-385265 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-385265 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-385265\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"504995\" commentParentId=\"385265\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/tanmay2904\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/772896/avatar/177ad04ce3e547bb.jpg'/> </a>\n <div><a href=\"/profile/tanmay2904\" title=\"Expert tanmay2904\" class=\"rated-user user-blue\">tanmay2904</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/12/2019 23:46\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-504995\" href=\"?#comment-504995\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-385265\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"504995\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"772896\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-504995\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Refer to this link, its a similar problem. <a href=\"https://discuss.codechef.com/t/magical-strings-editorial/11926\">https://discuss.codechef.com/t/magical-strings-editorial/11926</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-504995 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-504995 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-504995\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531139\" commentParentId=\"504995\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/RishabhKejariwal\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/777112/avatar/adb751f30e297e03.jpg'/> </a>\n <div><a href=\"/profile/RishabhKejariwal\" title=\"Expert RishabhKejariwal\" class=\"rated-user user-blue\">RishabhKejariwal</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2019 16:52\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531139\" href=\"?#comment-531139\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-504995\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"531139\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"777112\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531139\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks sir ! Your Comments Really Help me alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531139 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531139 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531139\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"531766\" commentParentId=\"531139\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ronaldocr7\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/877986/avatar/f10647e57d9661c7.jpg'/> </a>\n <div><a href=\"/profile/ronaldocr7\" title=\"Newbie ronaldocr7\" class=\"rated-user user-gray\">ronaldocr7</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/01/2019 14:37\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-531766\" href=\"?#comment-531766\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-531139\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"531766\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"531766\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"877986\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-531766\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thank you GOD ..........your comment helped whole coder community alot</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-531766 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-531766 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-531766\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"528440\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/VLADO\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/630234/avatar/e6872ed793f74338.jpg'/> </a>\n <div><a href=\"/profile/VLADO\" title=\"Expert VLADO\" class=\"rated-user user-blue\">VLADO</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/20/2019 10:43\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-528440\" href=\"?#comment-528440\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"528440\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"630234\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-528440\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The markdown seems to be broken.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-528440 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-528440 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-528440\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1040946\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Islam_Imad\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2855052/avatar/f0c85bec9e834bd3.jpg'/> </a>\n <div><a href=\"/profile/Islam_Imad\" title=\"Specialist Islam_Imad\" class=\"rated-user user-cyan\">Islam_Imad</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/26/2023 16:03\">3 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1040946\" href=\"?#comment-1040946\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1040946\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2855052\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1040946\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/151/submission/211135796\" title=\"Submission 211135796 by Islam_Imad\">211135796</a></p><p>Div2 D, here is the first solution based on DSU.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1040946 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1040946 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1040946\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3929\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: 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Marks"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Marks</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>1 second</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya, or Mr. Vasily Petrov is a dean of a department in a local university. After the winter exams he got his hands on a group's gradebook.</p><p>Overall the group has <span class=\"tex-span\"><i>n</i></span> students. They received marks for <span class=\"tex-span\"><i>m</i></span> subjects. Each student got a mark from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">9</span> (inclusive) for each subject.</p><p>Let's consider a student the <span class=\"tex-font-style-it\">best at some subject</span>, if there is no student who got a higher mark for this subject. Let's consider a student <span class=\"tex-font-style-it\">successful</span>, if there exists a subject he is the <span class=\"tex-font-style-it\">best at</span>.</p><p>Your task is to find the number of <span class=\"tex-font-style-it\">successful</span> students in the group.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>) — the number of students and the number of subjects, correspondingly. Next <span class=\"tex-span\"><i>n</i></span> lines each containing <span class=\"tex-span\"><i>m</i></span> characters describe the gradebook. Each character in the gradebook is a number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">9</span>. Note that the marks in a rows are not sepatated by spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of <span class=\"tex-font-style-it\">successful</span> students in the given group.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br/>223<br/>232<br/>112<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 5<br/>91728<br/>11828<br/>11111<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample test the student number <span class=\"tex-span\">1</span> is the best at subjects <span class=\"tex-span\">1</span> and <span class=\"tex-span\">3</span>, student <span class=\"tex-span\">2</span> is the best at subjects <span class=\"tex-span\">1</span> and <span class=\"tex-span\">2</span>, but student <span class=\"tex-span\">3</span> isn't the best at any subject.</p><p>In the second sample test each student is the best at at least one subject.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"07d106b1b2d732663e2dc2fd24b84092\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"07df7ea636cdbe445e0517a615206bf83136675b\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='07d106b1b2d732663e2dc2fd24b84092'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/152/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = $(this).hasClass(\"la-angle-right\");\r\n const params = {\r\n action: \"setCollapsed\",\r\n sidebarFrameSimpleClassName: \"ContestVirtualFrame\",\r\n collapsed\r\n };\r\n $.each($target[0].attributes, function(i, a) {\r\n const name = a.name;\r\n if (name.startsWith(\"data-extra-key-\")) {\r\n const key = a.value;\r\n const keyIndex = parseInt(name.substring(\"data-extra-key-\".length));\r\n const value = $target.attr(\"data-extra-value-\" + keyIndex);\r\n params[key] = value;\r\n }\r\n });\r\n $.post(dataPageUrl, params, function (result) {\r\n if (result[\"success\"] !== \"true\") {\r\n Codeforces.showMessage(\"Failed to save collapsed state.\");\r\n }\r\n }, \"json\");\r\n return false;\r\n });\r\n })\r\n </script>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Problem tags\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\"padding: 0.5em;\">\r\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Implementation problems, programming technics, simulation\">\r\n implementation\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *900\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='07d106b1b2d732663e2dc2fd24b84092'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"939\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='07d106b1b2d732663e2dc2fd24b84092'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"939\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3923\" title=\"Codeforces Round #108 (Div. 2)\" target=\"_blank\">Announcement</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"367:368\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3926\" title=\"Разбор задач Codeforces Round #108 (Div. 2)\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"948:949\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/152\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/152/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/152/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/152/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/152/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/152/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/152/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/152/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 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\"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_cb126ad4ee8c4d1f4766a4e223f5eed97f2b997b\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Marks</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>1 second</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya, or Mr. Vasily Petrov is a dean of a department in a local university. After the winter exams he got his hands on a group's gradebook.</p><p>Overall the group has <span class=\"tex-span\"><i>n</i></span> students. They received marks for <span class=\"tex-span\"><i>m</i></span> subjects. Each student got a mark from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">9</span> (inclusive) for each subject.</p><p>Let's consider a student the <span class=\"tex-font-style-it\">best at some subject</span>, if there is no student who got a higher mark for this subject. Let's consider a student <span class=\"tex-font-style-it\">successful</span>, if there exists a subject he is the <span class=\"tex-font-style-it\">best at</span>.</p><p>Your task is to find the number of <span class=\"tex-font-style-it\">successful</span> students in the group.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>) — the number of students and the number of subjects, correspondingly. Next <span class=\"tex-span\"><i>n</i></span> lines each containing <span class=\"tex-span\"><i>m</i></span> characters describe the gradebook. Each character in the gradebook is a number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">9</span>. Note that the marks in a rows are not sepatated by spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of <span class=\"tex-font-style-it\">successful</span> students in the given group.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br />223<br />232<br />112<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 5<br />91728<br />11828<br />11111<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample test the student number <span class=\"tex-span\">1</span> is the best at subjects <span class=\"tex-span\">1</span> and <span class=\"tex-span\">3</span>, student <span class=\"tex-span\">2</span> is the best at subjects <span class=\"tex-span\">1</span> and <span class=\"tex-span\">2</span>, but student <span class=\"tex-span\">3</span> isn't the best at any subject.</p><p>In the second sample test each student is the best at at least one subject.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=A]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n 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class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f898c2ea37ea4fba4315ca79ae6e074b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Gerald\">Gerald</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Gerald\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Gerald\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Gerald\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Gerald\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Gerald\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Gerald\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Gerald\" style=\"text-decoration:none;color:black !important;\">Gerald's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3940\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3926\"> <p>Разбор задач Codeforces Round #108 (Div. 2) </p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Gerald\" title=\"Master Gerald\" class=\"rated-user user-orange\">Gerald</a>,\r\n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h4><a href=\"/contest/152/problem/A\" title=\"Codeforces Round 108 (Div. 2)\">152A - Marks</a></h4><p>In this problem you should do exactly what is written in the statement. Here is rough code of solution:</p> <pre><code>for (int i = 0; i < n; ++i){ \n bool wasBest = false;\n for(int j = 0; j < m; ++j){\n bool isBest = true;\n for(int k = 0; k < n; ++k)\n if(a[k][j] > a[i][j])\n isBest = false;\n if(isBest) \n wasBest = true;\n }\n if(wasBest)\n ans++;\n} \n</code></pre><h4><a href=\"/contest/152/problem/B\" title=\"Codeforces Round 108 (Div. 2)\">152B - Steps</a></h4><p>Let's find a formula for the position <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> and vector <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, how many steps to stop the boy can do. You should use "almost" binary search, for example, see the code written by <a class=\"rated-user user-violet\" href=\"/profile/RAD\" title=\"Candidate Master RAD\">RAD</a>.</p> <pre><code>for (long long cof = 1100000000; cof; cof /= 2)\n while (onField(xc + cof * dx, yc + cof * dy)) {\n xc = xc + cof * dx;\n yc = yc + cof * dy;\n ans += cof;\n } \n</code></pre><h4><a href=\"/contest/152/problem/C\" title=\"Codeforces Round 108 (Div. 2)\">152C - Pocket Book</a></h4><p>In this task, it was necessary to understand that in position <span class=\"tex-span\">1</span> Vasya can get any name of a special form. More exactly, it's the name of form <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">3</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">4</sub></span> <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span>, where <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> — the first letter of any of the names, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> — the second letter of any of the names, <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span> — <span class=\"tex-span\"><i>m</i></span>-th letter of any of the names. Then the answer to the problem is the product of <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> is a number of different letters in the names placed in position <span class=\"tex-span\"><i>i</i></span>.</p><h4><a href=\"/contest/152/problem/D\" title=\"Codeforces Round 108 (Div. 2)\">152D - Frames</a></h4><p>It was necessary to understand if there are two borders or not.</p><p>Let's distinguish those <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates, in which there are at least <span class=\"tex-span\">3</span> consecutive symbols '#', becouse the length of each border is no less then <span class=\"tex-span\">3</span>. It is clear that the coordinates of the corners of borders should be chosen only from those selected <span class=\"tex-span\"><i>x</i></span> and <span class=\"tex-span\"><i>y</i></span>. In general, the various selected <span class=\"tex-span\"><i>x</i></span> no more then <span class=\"tex-span\">4</span> and various selected <span class=\"tex-span\"><i>y</i></span> no more then <span class=\"tex-span\">4</span>.</p><p>Except that case when the height or width of the first border is <span class=\"tex-span\">3</span>, and length of the second side of this border is more than <span class=\"tex-span\">3</span>, and one side of the second border fills a part of the inside first at least.</p><p>For example:</p> <pre>#######\n#######\n#######\n#.....#\n#######</pre><p>The first border:</p> <pre>#######\n#.....#\n#######\n.......\n.......</pre><p>The second border:</p> <pre>.......\n#######\n#.....#\n#.....#\n#######</pre><p>There are <span class=\"tex-span\">7</span> different <span class=\"tex-span\"><i>y</i></span>-coordinates in the example.</p><p>Carefully processed these cases separately, it is quite simple. (Let's choose <span class=\"tex-span\">4</span> <span class=\"tex-span\"><i>y</i></span>-coordinates: minimum, maximum, second minimum and second maximum).</p><p>Otherwise, if the amount selected <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates no more then <span class=\"tex-span\">4</span>, then let's choose opposite corners of the first and second borders and verify that the selected borders — the correct borders and there are no other characters '#'. Checking is carried out at <span class=\"tex-span\"><i>O</i>(<i>n</i> + <i>m</i>)</span> or <span class=\"tex-span\"><i>O</i>(1)</span> (using partial sums).</p><h4><a href=\"/contest/152/problem/E\" title=\"Codeforces Round 108 (Div. 2)\">152E - Garden</a></h4><p>The solution of this problem is based on dynamic programming. <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> — the value of the minimum correct concrete cover, if we consider as important elements only elements of the mask <span class=\"tex-span\"><i>mask</i></span>, and there are additionally covered the vertex <span class=\"tex-span\"><i>v</i> = (<i>i</i>, <i>j</i>)</span> of the field.</p><p>There are two types of transfers.</p><p>First of all we can, as if to cut coverage on the vertex <span class=\"tex-span\"><i>v</i></span>. Then you need to go through subpattern of vertex <span class=\"tex-span\"><i>submask</i></span>, which will go to the left coverage and make an optimizing transfer. Update <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> with the value <span class=\"tex-span\"><i>dp</i>[<i>submask</i>][<i>v</i>] + <i>dp</i>[<i>mask</i> ^ <i>submask</i>][<i>v</i>] - <i>cost</i>(<i>v</i>)</span>.</p><p>Second, perhaps in the vertex <span class=\"tex-span\"><i>v</i></span> in the optimal coverage mask <span class=\"tex-span\"><i>mask</i></span>, which covers the vertex <span class=\"tex-span\"><i>v</i></span>, you can not make the cut separating the set of vertices. In this case, this vertex forms something a kind of <>. And there a vertex <span class=\"tex-span\"><i>u</i></span> exists, on which we can make the cut, with the whole shortest path from a vertex <span class=\"tex-span\"><i>u</i></span> to <span class=\"tex-span\"><i>v</i></span> belongs to the optimal coverage. Let's precalculate the shortest paths between all pairs of cells. Now to make this transition, we should count the value of dynamics <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> for all vertices <span class=\"tex-span\"><i>v</i></span> only on the basis of the first transition. Now you can make the second transition. For all <span class=\"tex-span\"><i>u</i></span>, <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span>, update the value of <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>u</i>] + <i>dist</i>(<i>v</i>, <i>u</i>) - <i>cost</i>(<i>u</i>)</span>.</p><p>Let's process separately state in which exactly one bit in the mask, and the vertex which corresponding to this bit is equal to <span class=\"tex-span\"><i>v</i></span>. In this case the answer is equal to <span class=\"tex-span\"><i>cost</i>(<i>v</i>)</span>, of course.</p><p>Thus, each solution is obtained for the <span class=\"tex-span\"><i>O</i>(<i>min</i>(3<sup class=\"upper-index\"><i>k</i></sup>·<i>n</i>·<i>m</i>, 2<sup class=\"upper-index\"><i>k</i></sup>·(<i>n</i>·<i>m</i>)<sup class=\"upper-index\">2</sup>))</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/152\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 108 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-795-3940\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"795\",\n blogEntryId: \"3926\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=div+2\" class=\"tag notice\" style=\"text-decoration: none;\">div 2</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=editorial\" class=\"tag notice\" style=\"text-decoration: none;\">editorial</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+30</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Gerald\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Gerald\">\n Gerald\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3926#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3926#comments\">\n 26\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3950\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (15)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79734\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Acko\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4578/avatar/98a7ec7b1cb1a249.jpg'/> </a>\n <div><a href=\"/profile/Acko\" title=\"Candidate Master Acko\" class=\"rated-user user-violet\">Acko</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 02:07\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79734\" href=\"?#comment-79734\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79734\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4578\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79734\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was wondering if this idea is correct for task E ( I passed pretest in the competition but received WA10 at system test ). For each field of the matrix I run Dijkstra's algorithm with that field as source where cost ( u, v ) = Field[v] ( u and v are pairs of integers ). Then I reconstruct each paths from each of K important nodes to source and check if I have min path. Can you give me an example for which my idea fails or send me test #10. Thank you. :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79734 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79734 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79734\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79738\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/peking2\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/peking2\" title=\"Specialist peking2\" class=\"rated-user user-cyan\">peking2</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 04:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79738\" href=\"?#comment-79738\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79738\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"42638\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79738\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>First time to write Dijkstra for task E, but it seems not the correct solution. Overall solution is not necessary to be shortest path for each pair. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79738 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79738 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79738\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79741\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 06:25\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79741\" href=\"?#comment-79741\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79741\" revisionCount=\"5\" revision=\"5\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">5</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79741\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79741\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also have a solution similar to what they mentioned but a little different.<br />I try the following for each of the k! permutations of important nodes:</p><p>S={1stnode}<br />foreach i=2:k<br />1) Get shortest path between i and any of the nodes in S<br />2) Add cost of that path to total cost<br />3) Add nodes in that path to S<br />Minimize over all permutations.<br />It fails at test case 19 which is pretty large so I can even see fully. Can someone tell me what's wrong with the solution?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79741 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79741 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79741\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79761\" commentParentId=\"79741\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/coolinging\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/17136/avatar/8eebbd02d2734be7.jpg'/> </a>\n <div><a href=\"/profile/coolinging\" title=\"Master coolinging\" class=\"rated-user user-orange\">coolinging</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 10:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79761\" href=\"?#comment-79761\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79741\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79761\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79761\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"17136\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79761\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is a simple 3*3 example(1 are important squares):</p><p>2 1 2</p><p>1 6 1</p><p>2 1 2</p><p>The answer is: </p><p>10</p><p>.X.</p><p>XXX</p><p>.X.</p><p>Your solution's ans:</p><p>12</p><p>XXX</p><p>X.X</p><p>XXX</p><p>Some nodes are useless if there are only 2 important squares(Only nodes in the shortest path is useful),but useful if there are many important squares. (Just think the square 6 above.It isn't in the shortest path of any pair important squares,but it's benefit for all the important squares.) So considering only one node each time is incorrect.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79761 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79761 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79761\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79765\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 12:23\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79765\" href=\"?#comment-79765\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79765\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79765\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I see your point. Thanks a lot :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79765 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79765 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79765\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79793\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/dorellin\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/20026/avatar/9ab45d22868e4b56.jpg'/> </a>\n <div><a href=\"/profile/dorellin\" title=\"Candidate Master dorellin\" class=\"rated-user user-violet\">dorellin</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 19:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79793\" href=\"?#comment-79793\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79793\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"20026\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79793\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I tried this approach of minimization over all permutations of the k important nodes by doing the following:</p><p>for each permutation </p><p>i from 1:K-1:</p><p>calculate the sortest path from i to i+1 </p><p>all grid positions along the shortest path are reseted to 0</p><p>reset the grid to original after each permutation</p><p>gets WA on test case 10. I wonder if this idea is simply wrong. By the way, it works for the sample given by coolingging. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79793 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79793 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79793\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79745\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Oi.\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Oi.\" title=\"Expert Oi.\" class=\"rated-user user-blue\">Oi.</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 07:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79745\" href=\"?#comment-79745\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79745\" revisionCount=\"12\" revision=\"12\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">12</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79745\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"7\"\r\n data-commentUserId=\"8777\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+7</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79745\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I must confess I was a bit surprised at the "almost binary search" suggestion for problem B. You can just do straight divisions to check the maximum amount of steps possible!</p> <pre><code>if(dx > 0) ans = (n-xc)/dx;\nif(dx < 0) ans = (xc-1)/-dx;\nif(dy > 0) ans = min(ans, (m-yc)/dy);\nif(dy < 0) ans = min(ans, (yc-1)/-dy);\nxc += dx*ans;\nyc += dy*ans;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79745 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79745 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79745\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79749\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/NRCover\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/6450/avatar/bb89f3d49558861e.jpg'/> </a>\n <div><a href=\"/profile/NRCover\" title=\"Candidate Master NRCover\" class=\"rated-user user-violet\">NRCover</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 08:42\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79749\" href=\"?#comment-79749\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79749\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79749\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"24\"\r\n data-commentUserId=\"6450\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+24</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79749\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem E is a good problem. I feel that i learned a lot. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79749 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79749 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79749\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79823\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/CMH\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/CMH\" title=\"Expert CMH\" class=\"rated-user user-blue\">CMH</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/22/2012 07:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79823\" href=\"?#comment-79823\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79823\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"6\"\r\n data-commentUserId=\"39979\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+6</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79823\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think that E is a very good state of the compressed DP problem,and It is very similar with the 2008 Chinese Informatics Olympiad winter camp's test of trip ( tour plan ).I think tha they are all good.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79823 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79823 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79823\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80181\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/looool\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/looool\" title=\"Specialist looool\" class=\"rated-user user-cyan\">looool</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/25/2012 15:44\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80181\" href=\"?#comment-80181\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80181\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"25841\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80181\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can someone tell what's the meaning of "name number 1" in problem statement C -> <a href=\"//codeforces.com/contest/152/problem/C\"></a><a href=\"//codeforces.com/contest/152/problem/C\">Link</a></p><p>I will be grateful.</p><p>Thanks.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80181 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80181 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80181\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219284\" commentParentId=\"80181\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/25/2015 22:29\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219284\" href=\"?#comment-219284\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80181\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219284\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219284\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also can't get the idea!! Since we are swapping prefix and i & j should be >=1 & <=n. thats a problem for me!! Is this possible that, After swapping I've got a new word then I can also perform swap operation on this?? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219284 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219284 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219284\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219317\" commentParentId=\"219284\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/26/2015 08:56\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219317\" href=\"?#comment-219317\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-219284\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219317\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219317\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yes!! I've got it in my manner. Suppose, you have ABC & DEF .. then the possible different names are ABC,DEF,AEF,DBF,ABF,DEC,AEC,DBC=8 . Go with some example in paper.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219317 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219317 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219317\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"231780\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/sidhant\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/221909/avatar/8436b81921273f4.jpg'/> </a>\n <div><a href=\"/profile/sidhant\" title=\"Master sidhant\" class=\"rated-user user-orange\">sidhant</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/01/2015 18:17\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-231780\" href=\"?#comment-231780\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"231780\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"221909\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-231780\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Could anyone please give a more elaborate explanation of the solution of problem E.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-231780 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-231780 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-231780\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"295095\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shubhamgoyal__\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/shubhamgoyal__\" title=\"Candidate Master shubhamgoyal__\" class=\"rated-user user-violet\">shubhamgoyal__</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"May/20/2016 14:17\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-295095\" href=\"?#comment-295095\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"295095\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"321533\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-295095\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can somebody plz explain what does v represent in dp[mask][v] as explained in the editorial of Question E Garden</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-295095 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-295095 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-295095\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"954930\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nskybytskyi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/575628/avatar/e06ecd9e59495e05.jpg'/> </a>\n <div><a href=\"/profile/nskybytskyi\" title=\"International Master nskybytskyi\" class=\"rated-user user-orange\">nskybytskyi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/21/2022 17:26\">13 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-954930\" href=\"?#comment-954930\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"954930\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"575628\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-954930\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In the complexity analysis of problem E, you forgot to account for all pairs' shortest paths precomputation. Usually one would use Floyd-Warshall for APSP with a complexity of $$$O((n \\cdot m)^3)$$$. However, the graph in this problem is sparse with $$$|E| \\le 4 |V|$$$, making a series of $$$O(|V|)$$$ Dijkstras another viable solution with the overall complexity of $$$O((n \\cdot m)^2 \\log (n \\cdot m))$$$.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-954930 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-954930 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-954930\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3950\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":754,"cells":{"problem_id":{"kind":"string","value":"152B"},"contest":{"kind":"string","value":"152"},"problem":{"kind":"string","value":"B"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"B. Steps"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Steps</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day Vasya went out for a walk in the yard but there weren't any of his friends outside and he had no one to play touch and run. But the boy didn't lose the high spirits and decided to play touch and run with himself. You may ask: \"How did he do that?\" The answer is simple.</p><p>Vasya noticed that the yard is a rectangular <span class=\"tex-span\"><i>n</i> × <i>m</i></span> field. The squares have coordinates <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> (<span class=\"tex-span\">1 ≤ <i>x</i> ≤ <i>n</i>, 1 ≤ <i>y</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>x</i></span> is the index of the row and <span class=\"tex-span\"><i>y</i></span> is the index of the column.</p><p>Initially Vasya stands in the square with coordinates (<span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>c</i></sub>, <i>y</i><sub class=\"lower-index\"><i>c</i></sub></span>). To play, he has got a list of <span class=\"tex-span\"><i>k</i></span> vectors <span class=\"tex-span\">(<i>dx</i><sub class=\"lower-index\"><i>i</i></sub>, <i>dy</i><sub class=\"lower-index\"><i>i</i></sub>)</span> of non-zero length. The game goes like this. The boy considers all vectors in the order from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>k</i></span>, and consecutively chooses each vector as the current one. After the boy has chosen a current vector, he makes the maximally possible number of valid steps in the vector's direction (it is possible that he makes zero steps).</p><p>A <span class=\"tex-font-style-it\">step</span> is defined as one movement from the square where the boy is standing now, in the direction of the current vector. That is, if Vasya is positioned in square <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span>, and the current vector is <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, one step moves Vasya to square <span class=\"tex-span\">(<i>x</i> + <i>dx</i>, <i>y</i> + <i>dy</i>)</span>. A step is considered <span class=\"tex-font-style-it\">valid</span>, if the boy does not go out of the yard if he performs the step.</p><p>Vasya stepped on and on, on and on until he ran out of vectors in his list. Ha had been stepping for so long that he completely forgot how many steps he had made. Help the boy and count how many steps he had made.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the yard's sizes. The second line contains integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>c</i></sub></span> and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>c</i></sub></span> — the initial square's coordinates (<span class=\"tex-span\">1 ≤ <i>x</i><sub class=\"lower-index\"><i>c</i></sub> ≤ <i>n</i>, 1 ≤ <i>y</i><sub class=\"lower-index\"><i>c</i></sub> ≤ <i>m</i></span>).</p><p>The third line contains an integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of vectors. Then follow <span class=\"tex-span\"><i>k</i></span> lines, each of them contains two integers <span class=\"tex-span\"><i>dx</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>dy</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\">(|<i>dx</i><sub class=\"lower-index\"><i>i</i></sub>|, |<i>dy</i><sub class=\"lower-index\"><i>i</i></sub>| ≤ 10<sup class=\"upper-index\">9</sup>, |<i>dx</i>| + |<i>dy</i>| ≥ 1)</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of steps Vasya had made.</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br/>1 1<br/>3<br/>1 1<br/>1 1<br/>0 -2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br/>1 2<br/>1<br/>-1 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Vasya is initially positioned at square <span class=\"tex-span\">(1, 1)</span> and makes <span class=\"tex-span\">3</span> steps by the first vector <span class=\"tex-span\">(1, 1)</span>. So, he consecutively visits the squares <span class=\"tex-span\">(2, 2), (3, 3), (4, 4)</span>. Then he makes <span class=\"tex-span\">0</span> steps by the second vector <span class=\"tex-span\">(1, 1)</span>. He makes <span class=\"tex-span\">1</span> more step by the third vector <span class=\"tex-span\">(0, - 2)</span> and he ends up in square <span class=\"tex-span\">(4, 2)</span>. Overall, Vasya makes <span class=\"tex-span\">4</span> steps.</p><p>In the second sample Vasya is initially positioned in square <span class=\"tex-span\">(1, 2)</span> and makes <span class=\"tex-span\">0</span> steps by vector <span class=\"tex-span\">( - 1, 0)</span>, as the square with coordinates <span class=\"tex-span\">(0, 2)</span> is located outside the yard.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"f5bc48127272b994189edc3ae0a3bd02\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"07df7ea636cdbe445e0517a615206bf83136675b\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_7d7563c2462c6fecfb510bab58e8c06a9a68547d\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Steps</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day Vasya went out for a walk in the yard but there weren't any of his friends outside and he had no one to play touch and run. But the boy didn't lose the high spirits and decided to play touch and run with himself. You may ask: "How did he do that?" The answer is simple.</p><p>Vasya noticed that the yard is a rectangular <span class=\"tex-span\"><i>n</i> × <i>m</i></span> field. The squares have coordinates <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> (<span class=\"tex-span\">1 ≤ <i>x</i> ≤ <i>n</i>, 1 ≤ <i>y</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>x</i></span> is the index of the row and <span class=\"tex-span\"><i>y</i></span> is the index of the column.</p><p>Initially Vasya stands in the square with coordinates (<span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>c</i></sub>, <i>y</i><sub class=\"lower-index\"><i>c</i></sub></span>). To play, he has got a list of <span class=\"tex-span\"><i>k</i></span> vectors <span class=\"tex-span\">(<i>dx</i><sub class=\"lower-index\"><i>i</i></sub>, <i>dy</i><sub class=\"lower-index\"><i>i</i></sub>)</span> of non-zero length. The game goes like this. The boy considers all vectors in the order from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>k</i></span>, and consecutively chooses each vector as the current one. After the boy has chosen a current vector, he makes the maximally possible number of valid steps in the vector's direction (it is possible that he makes zero steps).</p><p>A <span class=\"tex-font-style-it\">step</span> is defined as one movement from the square where the boy is standing now, in the direction of the current vector. That is, if Vasya is positioned in square <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span>, and the current vector is <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, one step moves Vasya to square <span class=\"tex-span\">(<i>x</i> + <i>dx</i>, <i>y</i> + <i>dy</i>)</span>. A step is considered <span class=\"tex-font-style-it\">valid</span>, if the boy does not go out of the yard if he performs the step.</p><p>Vasya stepped on and on, on and on until he ran out of vectors in his list. Ha had been stepping for so long that he completely forgot how many steps he had made. Help the boy and count how many steps he had made.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the yard's sizes. The second line contains integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>c</i></sub></span> and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>c</i></sub></span> — the initial square's coordinates (<span class=\"tex-span\">1 ≤ <i>x</i><sub class=\"lower-index\"><i>c</i></sub> ≤ <i>n</i>, 1 ≤ <i>y</i><sub class=\"lower-index\"><i>c</i></sub> ≤ <i>m</i></span>).</p><p>The third line contains an integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of vectors. Then follow <span class=\"tex-span\"><i>k</i></span> lines, each of them contains two integers <span class=\"tex-span\"><i>dx</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>dy</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\">(|<i>dx</i><sub class=\"lower-index\"><i>i</i></sub>|, |<i>dy</i><sub class=\"lower-index\"><i>i</i></sub>| ≤ 10<sup class=\"upper-index\">9</sup>, |<i>dx</i>| + |<i>dy</i>| ≥ 1)</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of steps Vasya had made.</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br />1 1<br />3<br />1 1<br />1 1<br />0 -2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br />1 2<br />1<br />-1 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Vasya is initially positioned at square <span class=\"tex-span\">(1, 1)</span> and makes <span class=\"tex-span\">3</span> steps by the first vector <span class=\"tex-span\">(1, 1)</span>. So, he consecutively visits the squares <span class=\"tex-span\">(2, 2), (3, 3), (4, 4)</span>. Then he makes <span class=\"tex-span\">0</span> steps by the second vector <span class=\"tex-span\">(1, 1)</span>. He makes <span class=\"tex-span\">1</span> more step by the third vector <span class=\"tex-span\">(0, - 2)</span> and he ends up in square <span class=\"tex-span\">(4, 2)</span>. Overall, Vasya makes <span class=\"tex-span\">4</span> steps.</p><p>In the second sample Vasya is initially positioned in square <span class=\"tex-span\">(1, 2)</span> and makes <span class=\"tex-span\">0</span> steps by vector <span class=\"tex-span\">( - 1, 0)</span>, as the square with coordinates <span class=\"tex-span\">(0, 2)</span> is located outside the yard.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=B]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f898c2ea37ea4fba4315ca79ae6e074b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Gerald\">Gerald</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Gerald\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Gerald\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Gerald\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Gerald\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Gerald\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Gerald\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Gerald\" style=\"text-decoration:none;color:black !important;\">Gerald's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3940\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3926\"> <p>Разбор задач Codeforces Round #108 (Div. 2) </p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Gerald\" title=\"Master Gerald\" class=\"rated-user user-orange\">Gerald</a>,\r\n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h4><a href=\"/contest/152/problem/A\" title=\"Codeforces Round 108 (Div. 2)\">152A - Marks</a></h4><p>In this problem you should do exactly what is written in the statement. Here is rough code of solution:</p> <pre><code>for (int i = 0; i < n; ++i){ \n bool wasBest = false;\n for(int j = 0; j < m; ++j){\n bool isBest = true;\n for(int k = 0; k < n; ++k)\n if(a[k][j] > a[i][j])\n isBest = false;\n if(isBest) \n wasBest = true;\n }\n if(wasBest)\n ans++;\n} \n</code></pre><h4><a href=\"/contest/152/problem/B\" title=\"Codeforces Round 108 (Div. 2)\">152B - Steps</a></h4><p>Let's find a formula for the position <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> and vector <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, how many steps to stop the boy can do. You should use "almost" binary search, for example, see the code written by <a class=\"rated-user user-violet\" href=\"/profile/RAD\" title=\"Candidate Master RAD\">RAD</a>.</p> <pre><code>for (long long cof = 1100000000; cof; cof /= 2)\n while (onField(xc + cof * dx, yc + cof * dy)) {\n xc = xc + cof * dx;\n yc = yc + cof * dy;\n ans += cof;\n } \n</code></pre><h4><a href=\"/contest/152/problem/C\" title=\"Codeforces Round 108 (Div. 2)\">152C - Pocket Book</a></h4><p>In this task, it was necessary to understand that in position <span class=\"tex-span\">1</span> Vasya can get any name of a special form. More exactly, it's the name of form <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">3</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">4</sub></span> <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span>, where <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> — the first letter of any of the names, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> — the second letter of any of the names, <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span> — <span class=\"tex-span\"><i>m</i></span>-th letter of any of the names. Then the answer to the problem is the product of <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> is a number of different letters in the names placed in position <span class=\"tex-span\"><i>i</i></span>.</p><h4><a href=\"/contest/152/problem/D\" title=\"Codeforces Round 108 (Div. 2)\">152D - Frames</a></h4><p>It was necessary to understand if there are two borders or not.</p><p>Let's distinguish those <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates, in which there are at least <span class=\"tex-span\">3</span> consecutive symbols '#', becouse the length of each border is no less then <span class=\"tex-span\">3</span>. It is clear that the coordinates of the corners of borders should be chosen only from those selected <span class=\"tex-span\"><i>x</i></span> and <span class=\"tex-span\"><i>y</i></span>. In general, the various selected <span class=\"tex-span\"><i>x</i></span> no more then <span class=\"tex-span\">4</span> and various selected <span class=\"tex-span\"><i>y</i></span> no more then <span class=\"tex-span\">4</span>.</p><p>Except that case when the height or width of the first border is <span class=\"tex-span\">3</span>, and length of the second side of this border is more than <span class=\"tex-span\">3</span>, and one side of the second border fills a part of the inside first at least.</p><p>For example:</p> <pre>#######\n#######\n#######\n#.....#\n#######</pre><p>The first border:</p> <pre>#######\n#.....#\n#######\n.......\n.......</pre><p>The second border:</p> <pre>.......\n#######\n#.....#\n#.....#\n#######</pre><p>There are <span class=\"tex-span\">7</span> different <span class=\"tex-span\"><i>y</i></span>-coordinates in the example.</p><p>Carefully processed these cases separately, it is quite simple. (Let's choose <span class=\"tex-span\">4</span> <span class=\"tex-span\"><i>y</i></span>-coordinates: minimum, maximum, second minimum and second maximum).</p><p>Otherwise, if the amount selected <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates no more then <span class=\"tex-span\">4</span>, then let's choose opposite corners of the first and second borders and verify that the selected borders — the correct borders and there are no other characters '#'. Checking is carried out at <span class=\"tex-span\"><i>O</i>(<i>n</i> + <i>m</i>)</span> or <span class=\"tex-span\"><i>O</i>(1)</span> (using partial sums).</p><h4><a href=\"/contest/152/problem/E\" title=\"Codeforces Round 108 (Div. 2)\">152E - Garden</a></h4><p>The solution of this problem is based on dynamic programming. <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> — the value of the minimum correct concrete cover, if we consider as important elements only elements of the mask <span class=\"tex-span\"><i>mask</i></span>, and there are additionally covered the vertex <span class=\"tex-span\"><i>v</i> = (<i>i</i>, <i>j</i>)</span> of the field.</p><p>There are two types of transfers.</p><p>First of all we can, as if to cut coverage on the vertex <span class=\"tex-span\"><i>v</i></span>. Then you need to go through subpattern of vertex <span class=\"tex-span\"><i>submask</i></span>, which will go to the left coverage and make an optimizing transfer. Update <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> with the value <span class=\"tex-span\"><i>dp</i>[<i>submask</i>][<i>v</i>] + <i>dp</i>[<i>mask</i> ^ <i>submask</i>][<i>v</i>] - <i>cost</i>(<i>v</i>)</span>.</p><p>Second, perhaps in the vertex <span class=\"tex-span\"><i>v</i></span> in the optimal coverage mask <span class=\"tex-span\"><i>mask</i></span>, which covers the vertex <span class=\"tex-span\"><i>v</i></span>, you can not make the cut separating the set of vertices. In this case, this vertex forms something a kind of <>. And there a vertex <span class=\"tex-span\"><i>u</i></span> exists, on which we can make the cut, with the whole shortest path from a vertex <span class=\"tex-span\"><i>u</i></span> to <span class=\"tex-span\"><i>v</i></span> belongs to the optimal coverage. Let's precalculate the shortest paths between all pairs of cells. Now to make this transition, we should count the value of dynamics <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> for all vertices <span class=\"tex-span\"><i>v</i></span> only on the basis of the first transition. Now you can make the second transition. For all <span class=\"tex-span\"><i>u</i></span>, <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span>, update the value of <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>u</i>] + <i>dist</i>(<i>v</i>, <i>u</i>) - <i>cost</i>(<i>u</i>)</span>.</p><p>Let's process separately state in which exactly one bit in the mask, and the vertex which corresponding to this bit is equal to <span class=\"tex-span\"><i>v</i></span>. In this case the answer is equal to <span class=\"tex-span\"><i>cost</i>(<i>v</i>)</span>, of course.</p><p>Thus, each solution is obtained for the <span class=\"tex-span\"><i>O</i>(<i>min</i>(3<sup class=\"upper-index\"><i>k</i></sup>·<i>n</i>·<i>m</i>, 2<sup class=\"upper-index\"><i>k</i></sup>·(<i>n</i>·<i>m</i>)<sup class=\"upper-index\">2</sup>))</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/152\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 108 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-795-3940\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"795\",\n blogEntryId: \"3926\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=div+2\" class=\"tag notice\" style=\"text-decoration: none;\">div 2</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=editorial\" class=\"tag notice\" style=\"text-decoration: none;\">editorial</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+30</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Gerald\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Gerald\">\n Gerald\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3926#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3926#comments\">\n 26\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3950\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (15)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79734\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Acko\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4578/avatar/98a7ec7b1cb1a249.jpg'/> </a>\n <div><a href=\"/profile/Acko\" title=\"Candidate Master Acko\" class=\"rated-user user-violet\">Acko</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 02:07\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79734\" href=\"?#comment-79734\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79734\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4578\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79734\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was wondering if this idea is correct for task E ( I passed pretest in the competition but received WA10 at system test ). For each field of the matrix I run Dijkstra's algorithm with that field as source where cost ( u, v ) = Field[v] ( u and v are pairs of integers ). Then I reconstruct each paths from each of K important nodes to source and check if I have min path. Can you give me an example for which my idea fails or send me test #10. Thank you. :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79734 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79734 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79734\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79738\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/peking2\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/peking2\" title=\"Specialist peking2\" class=\"rated-user user-cyan\">peking2</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 04:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79738\" href=\"?#comment-79738\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79738\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"42638\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79738\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>First time to write Dijkstra for task E, but it seems not the correct solution. Overall solution is not necessary to be shortest path for each pair. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79738 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79738 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79738\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79741\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 06:25\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79741\" href=\"?#comment-79741\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79741\" revisionCount=\"5\" revision=\"5\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">5</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79741\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79741\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also have a solution similar to what they mentioned but a little different.<br />I try the following for each of the k! permutations of important nodes:</p><p>S={1stnode}<br />foreach i=2:k<br />1) Get shortest path between i and any of the nodes in S<br />2) Add cost of that path to total cost<br />3) Add nodes in that path to S<br />Minimize over all permutations.<br />It fails at test case 19 which is pretty large so I can even see fully. Can someone tell me what's wrong with the solution?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79741 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79741 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79741\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79761\" commentParentId=\"79741\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/coolinging\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/17136/avatar/8eebbd02d2734be7.jpg'/> </a>\n <div><a href=\"/profile/coolinging\" title=\"Master coolinging\" class=\"rated-user user-orange\">coolinging</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 10:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79761\" href=\"?#comment-79761\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79741\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79761\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79761\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"17136\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79761\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is a simple 3*3 example(1 are important squares):</p><p>2 1 2</p><p>1 6 1</p><p>2 1 2</p><p>The answer is: </p><p>10</p><p>.X.</p><p>XXX</p><p>.X.</p><p>Your solution's ans:</p><p>12</p><p>XXX</p><p>X.X</p><p>XXX</p><p>Some nodes are useless if there are only 2 important squares(Only nodes in the shortest path is useful),but useful if there are many important squares. (Just think the square 6 above.It isn't in the shortest path of any pair important squares,but it's benefit for all the important squares.) So considering only one node each time is incorrect.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79761 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79761 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79761\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79765\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 12:23\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79765\" href=\"?#comment-79765\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79765\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79765\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I see your point. Thanks a lot :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79765 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79765 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79765\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79793\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/dorellin\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/20026/avatar/9ab45d22868e4b56.jpg'/> </a>\n <div><a href=\"/profile/dorellin\" title=\"Candidate Master dorellin\" class=\"rated-user user-violet\">dorellin</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 19:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79793\" href=\"?#comment-79793\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79793\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"20026\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79793\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I tried this approach of minimization over all permutations of the k important nodes by doing the following:</p><p>for each permutation </p><p>i from 1:K-1:</p><p>calculate the sortest path from i to i+1 </p><p>all grid positions along the shortest path are reseted to 0</p><p>reset the grid to original after each permutation</p><p>gets WA on test case 10. I wonder if this idea is simply wrong. By the way, it works for the sample given by coolingging. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79793 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79793 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79793\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79745\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Oi.\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Oi.\" title=\"Expert Oi.\" class=\"rated-user user-blue\">Oi.</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 07:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79745\" href=\"?#comment-79745\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79745\" revisionCount=\"12\" revision=\"12\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">12</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79745\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"7\"\r\n data-commentUserId=\"8777\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+7</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79745\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I must confess I was a bit surprised at the "almost binary search" suggestion for problem B. You can just do straight divisions to check the maximum amount of steps possible!</p> <pre><code>if(dx > 0) ans = (n-xc)/dx;\nif(dx < 0) ans = (xc-1)/-dx;\nif(dy > 0) ans = min(ans, (m-yc)/dy);\nif(dy < 0) ans = min(ans, (yc-1)/-dy);\nxc += dx*ans;\nyc += dy*ans;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79745 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79745 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79745\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79749\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/NRCover\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/6450/avatar/bb89f3d49558861e.jpg'/> </a>\n <div><a href=\"/profile/NRCover\" title=\"Candidate Master NRCover\" class=\"rated-user user-violet\">NRCover</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 08:42\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79749\" href=\"?#comment-79749\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79749\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79749\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"24\"\r\n data-commentUserId=\"6450\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+24</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79749\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem E is a good problem. I feel that i learned a lot. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79749 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79749 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79749\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79823\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/CMH\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/CMH\" title=\"Expert CMH\" class=\"rated-user user-blue\">CMH</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/22/2012 07:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79823\" href=\"?#comment-79823\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79823\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"6\"\r\n data-commentUserId=\"39979\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+6</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79823\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think that E is a very good state of the compressed DP problem,and It is very similar with the 2008 Chinese Informatics Olympiad winter camp's test of trip ( tour plan ).I think tha they are all good.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79823 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79823 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79823\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80181\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/looool\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/looool\" title=\"Specialist looool\" class=\"rated-user user-cyan\">looool</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/25/2012 15:44\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80181\" href=\"?#comment-80181\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80181\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"25841\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80181\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can someone tell what's the meaning of "name number 1" in problem statement C -> <a href=\"//codeforces.com/contest/152/problem/C\"></a><a href=\"//codeforces.com/contest/152/problem/C\">Link</a></p><p>I will be grateful.</p><p>Thanks.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80181 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80181 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80181\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219284\" commentParentId=\"80181\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/25/2015 22:29\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219284\" href=\"?#comment-219284\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80181\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219284\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219284\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also can't get the idea!! Since we are swapping prefix and i & j should be >=1 & <=n. thats a problem for me!! Is this possible that, After swapping I've got a new word then I can also perform swap operation on this?? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219284 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219284 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219284\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219317\" commentParentId=\"219284\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/26/2015 08:56\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219317\" href=\"?#comment-219317\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-219284\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219317\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219317\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yes!! I've got it in my manner. Suppose, you have ABC & DEF .. then the possible different names are ABC,DEF,AEF,DBF,ABF,DEC,AEC,DBC=8 . Go with some example in paper.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219317 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219317 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219317\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"231780\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/sidhant\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/221909/avatar/8436b81921273f4.jpg'/> </a>\n <div><a href=\"/profile/sidhant\" title=\"Master sidhant\" class=\"rated-user user-orange\">sidhant</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/01/2015 18:17\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-231780\" href=\"?#comment-231780\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"231780\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"221909\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-231780\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Could anyone please give a more elaborate explanation of the solution of problem E.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-231780 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-231780 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-231780\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"295095\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shubhamgoyal__\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/shubhamgoyal__\" title=\"Candidate Master shubhamgoyal__\" class=\"rated-user user-violet\">shubhamgoyal__</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"May/20/2016 14:17\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-295095\" href=\"?#comment-295095\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"295095\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"321533\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-295095\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can somebody plz explain what does v represent in dp[mask][v] as explained in the editorial of Question E Garden</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-295095 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-295095 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-295095\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"954930\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nskybytskyi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/575628/avatar/e06ecd9e59495e05.jpg'/> </a>\n <div><a href=\"/profile/nskybytskyi\" title=\"International Master nskybytskyi\" class=\"rated-user user-orange\">nskybytskyi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/21/2022 17:26\">13 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-954930\" href=\"?#comment-954930\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"954930\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"575628\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-954930\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In the complexity analysis of problem E, you forgot to account for all pairs' shortest paths precomputation. Usually one would use Floyd-Warshall for APSP with a complexity of $$$O((n \\cdot m)^3)$$$. However, the graph in this problem is sparse with $$$|E| \\le 4 |V|$$$, making a series of $$$O(|V|)$$$ Dijkstras another viable solution with the overall complexity of $$$O((n \\cdot m)^2 \\log (n \\cdot m))$$$.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-954930 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-954930 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-954930\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3950\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 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Pocket Book"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Pocket Book</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day little Vasya found mom's pocket book. The book had <span class=\"tex-span\"><i>n</i></span> names of her friends and unusually enough, each name was exactly <span class=\"tex-span\"><i>m</i></span> letters long. Let's number the names from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span> in the order in which they are written.</p><p>As mom wasn't home, Vasya decided to play with names: he chose three integers <span class=\"tex-span\"><i>i</i></span>, <span class=\"tex-span\"><i>j</i></span>, <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>i</i> < <i>j</i> ≤ <i>n</i></span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>m</i></span>), then he took names number <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> and swapped their prefixes of length <span class=\"tex-span\"><i>k</i></span>. For example, if we take names \"<span class=\"tex-font-style-tt\">CBDAD</span>\" and \"<span class=\"tex-font-style-tt\">AABRD</span>\" and swap their prefixes with the length of <span class=\"tex-span\">3</span>, the result will be names \"<span class=\"tex-font-style-tt\">AABAD</span>\" and \"<span class=\"tex-font-style-tt\">CBDRD</span>\".</p><p>You wonder how many different names Vasya can write instead of name number <span class=\"tex-span\">1</span>, if Vasya is allowed to perform any number of the described actions. As Vasya performs each action, he chooses numbers <span class=\"tex-span\"><i>i</i></span>, <span class=\"tex-span\"><i>j</i></span>, <span class=\"tex-span\"><i>k</i></span> independently from the previous moves and his choice is based entirely on his will. The sought number can be very large, so you should only find it modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>) — the number of names and the length of each name, correspondingly. Then <span class=\"tex-span\"><i>n</i></span> lines contain names, each name consists of exactly <span class=\"tex-span\"><i>m</i></span> uppercase Latin letters.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of different names that could end up in position number <span class=\"tex-span\">1</span> in the pocket book after the applying the procedures described above. Print the number modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2 3<br/>AAB<br/>BAA<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br/>ABABA<br/>BCGDG<br/>AAAAA<br/>YABSA<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>216<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Vasya can get the following names in the position number <span class=\"tex-span\">1</span>: \"AAB\", \"AAA\", \"BAA\" and \"BAB\".</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"58f8fb1f3256613b1a0458f85463dc38\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"07df7ea636cdbe445e0517a615206bf83136675b\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/152\">Codeforces Round 108 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='58f8fb1f3256613b1a0458f85463dc38'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/152/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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href=\"/blog/entry/3923\" title=\"Codeforces Round #108 (Div. 2)\" target=\"_blank\">Announcement</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"367:368\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3926\" title=\"Разбор задач Codeforces Round #108 (Div. 2)\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"948:949\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div 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right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Pocket Book</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day little Vasya found mom's pocket book. The book had <span class=\"tex-span\"><i>n</i></span> names of her friends and unusually enough, each name was exactly <span class=\"tex-span\"><i>m</i></span> letters long. Let's number the names from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span> in the order in which they are written.</p><p>As mom wasn't home, Vasya decided to play with names: he chose three integers <span class=\"tex-span\"><i>i</i></span>, <span class=\"tex-span\"><i>j</i></span>, <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>i</i> < <i>j</i> ≤ <i>n</i></span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>m</i></span>), then he took names number <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> and swapped their prefixes of length <span class=\"tex-span\"><i>k</i></span>. For example, if we take names "<span class=\"tex-font-style-tt\">CBDAD</span>" and "<span class=\"tex-font-style-tt\">AABRD</span>" and swap their prefixes with the length of <span class=\"tex-span\">3</span>, the result will be names "<span class=\"tex-font-style-tt\">AABAD</span>" and "<span class=\"tex-font-style-tt\">CBDRD</span>".</p><p>You wonder how many different names Vasya can write instead of name number <span class=\"tex-span\">1</span>, if Vasya is allowed to perform any number of the described actions. As Vasya performs each action, he chooses numbers <span class=\"tex-span\"><i>i</i></span>, <span class=\"tex-span\"><i>j</i></span>, <span class=\"tex-span\"><i>k</i></span> independently from the previous moves and his choice is based entirely on his will. The sought number can be very large, so you should only find it modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>) — the number of names and the length of each name, correspondingly. Then <span class=\"tex-span\"><i>n</i></span> lines contain names, each name consists of exactly <span class=\"tex-span\"><i>m</i></span> uppercase Latin letters.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of different names that could end up in position number <span class=\"tex-span\">1</span> in the pocket book after the applying the procedures described above. Print the number modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2 3<br />AAB<br />BAA<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br />ABABA<br />BCGDG<br />AAAAA<br />YABSA<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>216<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Vasya can get the following names in the position number <span class=\"tex-span\">1</span>: "AAB", "AAA", "BAA" and "BAB".</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f898c2ea37ea4fba4315ca79ae6e074b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Gerald\">Gerald</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Gerald\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Gerald\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Gerald\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Gerald\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Gerald\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Gerald\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Gerald\" style=\"text-decoration:none;color:black !important;\">Gerald's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3940\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3926\"> <p>Разбор задач Codeforces Round #108 (Div. 2) </p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Gerald\" title=\"Master Gerald\" class=\"rated-user user-orange\">Gerald</a>,\r\n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h4><a href=\"/contest/152/problem/A\" title=\"Codeforces Round 108 (Div. 2)\">152A - Marks</a></h4><p>In this problem you should do exactly what is written in the statement. Here is rough code of solution:</p> <pre><code>for (int i = 0; i < n; ++i){ \n bool wasBest = false;\n for(int j = 0; j < m; ++j){\n bool isBest = true;\n for(int k = 0; k < n; ++k)\n if(a[k][j] > a[i][j])\n isBest = false;\n if(isBest) \n wasBest = true;\n }\n if(wasBest)\n ans++;\n} \n</code></pre><h4><a href=\"/contest/152/problem/B\" title=\"Codeforces Round 108 (Div. 2)\">152B - Steps</a></h4><p>Let's find a formula for the position <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> and vector <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, how many steps to stop the boy can do. You should use "almost" binary search, for example, see the code written by <a class=\"rated-user user-violet\" href=\"/profile/RAD\" title=\"Candidate Master RAD\">RAD</a>.</p> <pre><code>for (long long cof = 1100000000; cof; cof /= 2)\n while (onField(xc + cof * dx, yc + cof * dy)) {\n xc = xc + cof * dx;\n yc = yc + cof * dy;\n ans += cof;\n } \n</code></pre><h4><a href=\"/contest/152/problem/C\" title=\"Codeforces Round 108 (Div. 2)\">152C - Pocket Book</a></h4><p>In this task, it was necessary to understand that in position <span class=\"tex-span\">1</span> Vasya can get any name of a special form. More exactly, it's the name of form <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">3</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">4</sub></span> <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span>, where <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> — the first letter of any of the names, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> — the second letter of any of the names, <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span> — <span class=\"tex-span\"><i>m</i></span>-th letter of any of the names. Then the answer to the problem is the product of <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> is a number of different letters in the names placed in position <span class=\"tex-span\"><i>i</i></span>.</p><h4><a href=\"/contest/152/problem/D\" title=\"Codeforces Round 108 (Div. 2)\">152D - Frames</a></h4><p>It was necessary to understand if there are two borders or not.</p><p>Let's distinguish those <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates, in which there are at least <span class=\"tex-span\">3</span> consecutive symbols '#', becouse the length of each border is no less then <span class=\"tex-span\">3</span>. It is clear that the coordinates of the corners of borders should be chosen only from those selected <span class=\"tex-span\"><i>x</i></span> and <span class=\"tex-span\"><i>y</i></span>. In general, the various selected <span class=\"tex-span\"><i>x</i></span> no more then <span class=\"tex-span\">4</span> and various selected <span class=\"tex-span\"><i>y</i></span> no more then <span class=\"tex-span\">4</span>.</p><p>Except that case when the height or width of the first border is <span class=\"tex-span\">3</span>, and length of the second side of this border is more than <span class=\"tex-span\">3</span>, and one side of the second border fills a part of the inside first at least.</p><p>For example:</p> <pre>#######\n#######\n#######\n#.....#\n#######</pre><p>The first border:</p> <pre>#######\n#.....#\n#######\n.......\n.......</pre><p>The second border:</p> <pre>.......\n#######\n#.....#\n#.....#\n#######</pre><p>There are <span class=\"tex-span\">7</span> different <span class=\"tex-span\"><i>y</i></span>-coordinates in the example.</p><p>Carefully processed these cases separately, it is quite simple. (Let's choose <span class=\"tex-span\">4</span> <span class=\"tex-span\"><i>y</i></span>-coordinates: minimum, maximum, second minimum and second maximum).</p><p>Otherwise, if the amount selected <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates no more then <span class=\"tex-span\">4</span>, then let's choose opposite corners of the first and second borders and verify that the selected borders — the correct borders and there are no other characters '#'. Checking is carried out at <span class=\"tex-span\"><i>O</i>(<i>n</i> + <i>m</i>)</span> or <span class=\"tex-span\"><i>O</i>(1)</span> (using partial sums).</p><h4><a href=\"/contest/152/problem/E\" title=\"Codeforces Round 108 (Div. 2)\">152E - Garden</a></h4><p>The solution of this problem is based on dynamic programming. <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> — the value of the minimum correct concrete cover, if we consider as important elements only elements of the mask <span class=\"tex-span\"><i>mask</i></span>, and there are additionally covered the vertex <span class=\"tex-span\"><i>v</i> = (<i>i</i>, <i>j</i>)</span> of the field.</p><p>There are two types of transfers.</p><p>First of all we can, as if to cut coverage on the vertex <span class=\"tex-span\"><i>v</i></span>. Then you need to go through subpattern of vertex <span class=\"tex-span\"><i>submask</i></span>, which will go to the left coverage and make an optimizing transfer. Update <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> with the value <span class=\"tex-span\"><i>dp</i>[<i>submask</i>][<i>v</i>] + <i>dp</i>[<i>mask</i> ^ <i>submask</i>][<i>v</i>] - <i>cost</i>(<i>v</i>)</span>.</p><p>Second, perhaps in the vertex <span class=\"tex-span\"><i>v</i></span> in the optimal coverage mask <span class=\"tex-span\"><i>mask</i></span>, which covers the vertex <span class=\"tex-span\"><i>v</i></span>, you can not make the cut separating the set of vertices. In this case, this vertex forms something a kind of <>. And there a vertex <span class=\"tex-span\"><i>u</i></span> exists, on which we can make the cut, with the whole shortest path from a vertex <span class=\"tex-span\"><i>u</i></span> to <span class=\"tex-span\"><i>v</i></span> belongs to the optimal coverage. Let's precalculate the shortest paths between all pairs of cells. Now to make this transition, we should count the value of dynamics <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> for all vertices <span class=\"tex-span\"><i>v</i></span> only on the basis of the first transition. Now you can make the second transition. For all <span class=\"tex-span\"><i>u</i></span>, <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span>, update the value of <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>u</i>] + <i>dist</i>(<i>v</i>, <i>u</i>) - <i>cost</i>(<i>u</i>)</span>.</p><p>Let's process separately state in which exactly one bit in the mask, and the vertex which corresponding to this bit is equal to <span class=\"tex-span\"><i>v</i></span>. In this case the answer is equal to <span class=\"tex-span\"><i>cost</i>(<i>v</i>)</span>, of course.</p><p>Thus, each solution is obtained for the <span class=\"tex-span\"><i>O</i>(<i>min</i>(3<sup class=\"upper-index\"><i>k</i></sup>·<i>n</i>·<i>m</i>, 2<sup class=\"upper-index\"><i>k</i></sup>·(<i>n</i>·<i>m</i>)<sup class=\"upper-index\">2</sup>))</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/152\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 108 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-795-3940\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"795\",\n blogEntryId: \"3926\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=div+2\" class=\"tag notice\" style=\"text-decoration: none;\">div 2</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=editorial\" class=\"tag notice\" style=\"text-decoration: none;\">editorial</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+30</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Gerald\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Gerald\">\n Gerald\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3926#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3926#comments\">\n 26\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3950\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (15)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79734\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Acko\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4578/avatar/98a7ec7b1cb1a249.jpg'/> </a>\n <div><a href=\"/profile/Acko\" title=\"Candidate Master Acko\" class=\"rated-user user-violet\">Acko</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 02:07\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79734\" href=\"?#comment-79734\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79734\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4578\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79734\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was wondering if this idea is correct for task E ( I passed pretest in the competition but received WA10 at system test ). For each field of the matrix I run Dijkstra's algorithm with that field as source where cost ( u, v ) = Field[v] ( u and v are pairs of integers ). Then I reconstruct each paths from each of K important nodes to source and check if I have min path. Can you give me an example for which my idea fails or send me test #10. Thank you. :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79734 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79734 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79734\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79738\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/peking2\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/peking2\" title=\"Specialist peking2\" class=\"rated-user user-cyan\">peking2</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 04:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79738\" href=\"?#comment-79738\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79738\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"42638\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79738\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>First time to write Dijkstra for task E, but it seems not the correct solution. Overall solution is not necessary to be shortest path for each pair. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79738 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79738 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79738\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79741\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 06:25\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79741\" href=\"?#comment-79741\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79741\" revisionCount=\"5\" revision=\"5\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">5</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79741\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79741\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also have a solution similar to what they mentioned but a little different.<br />I try the following for each of the k! permutations of important nodes:</p><p>S={1stnode}<br />foreach i=2:k<br />1) Get shortest path between i and any of the nodes in S<br />2) Add cost of that path to total cost<br />3) Add nodes in that path to S<br />Minimize over all permutations.<br />It fails at test case 19 which is pretty large so I can even see fully. Can someone tell me what's wrong with the solution?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79741 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79741 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79741\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79761\" commentParentId=\"79741\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/coolinging\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/17136/avatar/8eebbd02d2734be7.jpg'/> </a>\n <div><a href=\"/profile/coolinging\" title=\"Master coolinging\" class=\"rated-user user-orange\">coolinging</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 10:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79761\" href=\"?#comment-79761\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79741\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79761\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79761\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"17136\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79761\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is a simple 3*3 example(1 are important squares):</p><p>2 1 2</p><p>1 6 1</p><p>2 1 2</p><p>The answer is: </p><p>10</p><p>.X.</p><p>XXX</p><p>.X.</p><p>Your solution's ans:</p><p>12</p><p>XXX</p><p>X.X</p><p>XXX</p><p>Some nodes are useless if there are only 2 important squares(Only nodes in the shortest path is useful),but useful if there are many important squares. (Just think the square 6 above.It isn't in the shortest path of any pair important squares,but it's benefit for all the important squares.) So considering only one node each time is incorrect.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79761 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79761 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79761\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79765\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 12:23\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79765\" href=\"?#comment-79765\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79765\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79765\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I see your point. Thanks a lot :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79765 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79765 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79765\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79793\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/dorellin\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/20026/avatar/9ab45d22868e4b56.jpg'/> </a>\n <div><a href=\"/profile/dorellin\" title=\"Candidate Master dorellin\" class=\"rated-user user-violet\">dorellin</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 19:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79793\" href=\"?#comment-79793\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79793\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"20026\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79793\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I tried this approach of minimization over all permutations of the k important nodes by doing the following:</p><p>for each permutation </p><p>i from 1:K-1:</p><p>calculate the sortest path from i to i+1 </p><p>all grid positions along the shortest path are reseted to 0</p><p>reset the grid to original after each permutation</p><p>gets WA on test case 10. I wonder if this idea is simply wrong. By the way, it works for the sample given by coolingging. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79793 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79793 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79793\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79745\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Oi.\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Oi.\" title=\"Expert Oi.\" class=\"rated-user user-blue\">Oi.</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 07:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79745\" href=\"?#comment-79745\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79745\" revisionCount=\"12\" revision=\"12\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">12</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79745\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"7\"\r\n data-commentUserId=\"8777\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+7</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79745\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I must confess I was a bit surprised at the "almost binary search" suggestion for problem B. You can just do straight divisions to check the maximum amount of steps possible!</p> <pre><code>if(dx > 0) ans = (n-xc)/dx;\nif(dx < 0) ans = (xc-1)/-dx;\nif(dy > 0) ans = min(ans, (m-yc)/dy);\nif(dy < 0) ans = min(ans, (yc-1)/-dy);\nxc += dx*ans;\nyc += dy*ans;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79745 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79745 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79745\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79749\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/NRCover\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/6450/avatar/bb89f3d49558861e.jpg'/> </a>\n <div><a href=\"/profile/NRCover\" title=\"Candidate Master NRCover\" class=\"rated-user user-violet\">NRCover</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 08:42\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79749\" href=\"?#comment-79749\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79749\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79749\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"24\"\r\n data-commentUserId=\"6450\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+24</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79749\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem E is a good problem. I feel that i learned a lot. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79749 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79749 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79749\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79823\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/CMH\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/CMH\" title=\"Expert CMH\" class=\"rated-user user-blue\">CMH</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/22/2012 07:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79823\" href=\"?#comment-79823\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79823\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"6\"\r\n data-commentUserId=\"39979\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+6</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79823\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think that E is a very good state of the compressed DP problem,and It is very similar with the 2008 Chinese Informatics Olympiad winter camp's test of trip ( tour plan ).I think tha they are all good.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79823 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79823 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79823\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80181\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/looool\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/looool\" title=\"Specialist looool\" class=\"rated-user user-cyan\">looool</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/25/2012 15:44\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80181\" href=\"?#comment-80181\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80181\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"25841\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80181\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can someone tell what's the meaning of "name number 1" in problem statement C -> <a href=\"//codeforces.com/contest/152/problem/C\"></a><a href=\"//codeforces.com/contest/152/problem/C\">Link</a></p><p>I will be grateful.</p><p>Thanks.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80181 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80181 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80181\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219284\" commentParentId=\"80181\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/25/2015 22:29\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219284\" href=\"?#comment-219284\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80181\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219284\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219284\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also can't get the idea!! Since we are swapping prefix and i & j should be >=1 & <=n. thats a problem for me!! Is this possible that, After swapping I've got a new word then I can also perform swap operation on this?? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219284 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219284 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219284\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219317\" commentParentId=\"219284\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/26/2015 08:56\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219317\" href=\"?#comment-219317\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-219284\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219317\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219317\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yes!! I've got it in my manner. Suppose, you have ABC & DEF .. then the possible different names are ABC,DEF,AEF,DBF,ABF,DEC,AEC,DBC=8 . Go with some example in paper.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219317 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219317 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219317\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"231780\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/sidhant\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/221909/avatar/8436b81921273f4.jpg'/> </a>\n <div><a href=\"/profile/sidhant\" title=\"Master sidhant\" class=\"rated-user user-orange\">sidhant</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/01/2015 18:17\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-231780\" href=\"?#comment-231780\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"231780\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"221909\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-231780\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Could anyone please give a more elaborate explanation of the solution of problem E.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-231780 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-231780 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-231780\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"295095\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shubhamgoyal__\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/shubhamgoyal__\" title=\"Candidate Master shubhamgoyal__\" class=\"rated-user user-violet\">shubhamgoyal__</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"May/20/2016 14:17\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-295095\" href=\"?#comment-295095\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"295095\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"321533\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-295095\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can somebody plz explain what does v represent in dp[mask][v] as explained in the editorial of Question E Garden</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-295095 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-295095 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-295095\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"954930\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nskybytskyi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/575628/avatar/e06ecd9e59495e05.jpg'/> </a>\n <div><a href=\"/profile/nskybytskyi\" title=\"International Master nskybytskyi\" class=\"rated-user user-orange\">nskybytskyi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/21/2022 17:26\">13 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-954930\" href=\"?#comment-954930\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"954930\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"575628\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-954930\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In the complexity analysis of problem E, you forgot to account for all pairs' shortest paths precomputation. Usually one would use Floyd-Warshall for APSP with a complexity of $$$O((n \\cdot m)^3)$$$. However, the graph in this problem is sparse with $$$|E| \\le 4 |V|$$$, making a series of $$$O(|V|)$$$ Dijkstras another viable solution with the overall complexity of $$$O((n \\cdot m)^2 \\log (n \\cdot m))$$$.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-954930 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-954930 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-954930\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3950\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 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Frames"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Frames</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day Vasya got hold of a sheet of checkered paper <span class=\"tex-span\"><i>n</i> × <i>m</i></span> squares in size. Our Vasya adores geometrical figures, so he painted two rectangles on the paper. The rectangles' sides are parallel to the coordinates' axes, also the length of each side of each rectangle is no less than 3 squares and the sides are painted by the grid lines. The sides can also be part of the sheet of paper's edge. Then Vasya hatched all squares on the rectangles' <span class=\"tex-font-style-underline\">frames</span>.</p><p>Let's define a rectangle's frame as the set of squares <span class=\"tex-font-style-bf\">inside</span> the rectangle that share at least one side with its border.</p><p>A little later Vasya found a sheet of paper of exactly the same size and couldn't guess whether it is the same sheet of paper or a different one. So, he asked you to check whether the sheet of paper he had found contains two painted frames and nothing besides them.</p><p>Please note that the frames painted by Vasya can arbitrarily intersect, overlap or even completely coincide.</p><p>The coordinates on the sheet of paper are introduced in such a way that the <span class=\"tex-span\"><i>X</i></span> axis goes from top to bottom, the <span class=\"tex-span\"><i>x</i></span> coordinates of the squares' numbers take values from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span> and the <span class=\"tex-span\"><i>Y</i></span> axis goes from the left to the right and the <span class=\"tex-span\"><i>y</i></span> coordinates of the squares' numbers take values from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>m</i></span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">3 ≤ <i>n</i>, <i>m</i> ≤ 1000</span>) — the sizes of the sheet of paper Vasya found. Next <span class=\"tex-span\"><i>n</i></span> lines, each consisting of <span class=\"tex-span\"><i>m</i></span> symbols \"<span class=\"tex-font-style-tt\">.</span>\" (dot) and \"<span class=\"tex-font-style-tt\">#</span>\" (number sign), describe the found sheet of paper. The symbol \"<span class=\"tex-font-style-tt\">#</span>\" represents a hatched square and the symbol \"<span class=\"tex-font-style-tt\">.</span>\" represents a non-hatched square.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the single word \"<span class=\"tex-font-style-tt\">YES</span>\" or \"<span class=\"tex-font-style-tt\">NO</span>\", meaning whether it is true that the found sheet of paper has two frames painted on it. If the answer is positive, then print in the second line <span class=\"tex-span\">4</span> integers: the coordinates of the upper left and lower right corners of the first frame. In the third line print <span class=\"tex-span\">4</span> integers: the coordinates of the upper left and the lower right corners of the second frame. If there are multiple answers, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br/>#####<br/>#.#.#<br/>###.#<br/>#####<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>YES<br/>1 1 3 3<br/>1 1 4 5<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 6<br/>...###<br/>...###<br/>#####.<br/>#...#.<br/>#####.<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>NO<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample there are two frames on the picture. The first one is:</p><pre class=\"verbatim\">###..<br/>#.#..<br/>###..<br/>.....<br/></pre><p>The second one is:</p><pre class=\"verbatim\">#####<br/>#...#<br/>#...#<br/>#####<br/></pre><p>In the second sample the painted figures are not frames. 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href=\"/blog/entry/3923\" title=\"Codeforces Round #108 (Div. 2)\" target=\"_blank\">Announcement</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"367:368\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3926\" title=\"Разбор задач Codeforces Round #108 (Div. 2)\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"948:949\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div 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text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_62bf496b7f2259328eccd3ac5d113e327706770f\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Frames</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day Vasya got hold of a sheet of checkered paper <span class=\"tex-span\"><i>n</i> × <i>m</i></span> squares in size. Our Vasya adores geometrical figures, so he painted two rectangles on the paper. The rectangles' sides are parallel to the coordinates' axes, also the length of each side of each rectangle is no less than 3 squares and the sides are painted by the grid lines. The sides can also be part of the sheet of paper's edge. Then Vasya hatched all squares on the rectangles' <span class=\"tex-font-style-underline\">frames</span>.</p><p>Let's define a rectangle's frame as the set of squares <span class=\"tex-font-style-bf\">inside</span> the rectangle that share at least one side with its border.</p><p>A little later Vasya found a sheet of paper of exactly the same size and couldn't guess whether it is the same sheet of paper or a different one. So, he asked you to check whether the sheet of paper he had found contains two painted frames and nothing besides them.</p><p>Please note that the frames painted by Vasya can arbitrarily intersect, overlap or even completely coincide.</p><p>The coordinates on the sheet of paper are introduced in such a way that the <span class=\"tex-span\"><i>X</i></span> axis goes from top to bottom, the <span class=\"tex-span\"><i>x</i></span> coordinates of the squares' numbers take values from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span> and the <span class=\"tex-span\"><i>Y</i></span> axis goes from the left to the right and the <span class=\"tex-span\"><i>y</i></span> coordinates of the squares' numbers take values from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>m</i></span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">3 ≤ <i>n</i>, <i>m</i> ≤ 1000</span>) — the sizes of the sheet of paper Vasya found. Next <span class=\"tex-span\"><i>n</i></span> lines, each consisting of <span class=\"tex-span\"><i>m</i></span> symbols "<span class=\"tex-font-style-tt\">.</span>" (dot) and "<span class=\"tex-font-style-tt\">#</span>" (number sign), describe the found sheet of paper. The symbol "<span class=\"tex-font-style-tt\">#</span>" represents a hatched square and the symbol "<span class=\"tex-font-style-tt\">.</span>" represents a non-hatched square.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the single word "<span class=\"tex-font-style-tt\">YES</span>" or "<span class=\"tex-font-style-tt\">NO</span>", meaning whether it is true that the found sheet of paper has two frames painted on it. If the answer is positive, then print in the second line <span class=\"tex-span\">4</span> integers: the coordinates of the upper left and lower right corners of the first frame. In the third line print <span class=\"tex-span\">4</span> integers: the coordinates of the upper left and the lower right corners of the second frame. If there are multiple answers, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br />#####<br />#.#.#<br />###.#<br />#####<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>YES<br />1 1 3 3<br />1 1 4 5<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 6<br />...###<br />...###<br />#####.<br />#...#.<br />#####.<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>NO<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample there are two frames on the picture. The first one is:</p><pre class=\"verbatim\">###..<br />#.#..<br />###..<br />.....<br /></pre><p>The second one is:</p><pre class=\"verbatim\">#####<br />#...#<br />#...#<br />#####<br /></pre><p>In the second sample the painted figures are not frames. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" 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class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f898c2ea37ea4fba4315ca79ae6e074b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Gerald\">Gerald</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Gerald\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Gerald\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Gerald\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Gerald\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Gerald\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Gerald\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Gerald\" style=\"text-decoration:none;color:black !important;\">Gerald's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3940\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3926\"> <p>Разбор задач Codeforces Round #108 (Div. 2) </p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Gerald\" title=\"Master Gerald\" class=\"rated-user user-orange\">Gerald</a>,\r\n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h4><a href=\"/contest/152/problem/A\" title=\"Codeforces Round 108 (Div. 2)\">152A - Marks</a></h4><p>In this problem you should do exactly what is written in the statement. Here is rough code of solution:</p> <pre><code>for (int i = 0; i < n; ++i){ \n bool wasBest = false;\n for(int j = 0; j < m; ++j){\n bool isBest = true;\n for(int k = 0; k < n; ++k)\n if(a[k][j] > a[i][j])\n isBest = false;\n if(isBest) \n wasBest = true;\n }\n if(wasBest)\n ans++;\n} \n</code></pre><h4><a href=\"/contest/152/problem/B\" title=\"Codeforces Round 108 (Div. 2)\">152B - Steps</a></h4><p>Let's find a formula for the position <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> and vector <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, how many steps to stop the boy can do. You should use "almost" binary search, for example, see the code written by <a class=\"rated-user user-violet\" href=\"/profile/RAD\" title=\"Candidate Master RAD\">RAD</a>.</p> <pre><code>for (long long cof = 1100000000; cof; cof /= 2)\n while (onField(xc + cof * dx, yc + cof * dy)) {\n xc = xc + cof * dx;\n yc = yc + cof * dy;\n ans += cof;\n } \n</code></pre><h4><a href=\"/contest/152/problem/C\" title=\"Codeforces Round 108 (Div. 2)\">152C - Pocket Book</a></h4><p>In this task, it was necessary to understand that in position <span class=\"tex-span\">1</span> Vasya can get any name of a special form. More exactly, it's the name of form <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">3</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">4</sub></span> <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span>, where <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> — the first letter of any of the names, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> — the second letter of any of the names, <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span> — <span class=\"tex-span\"><i>m</i></span>-th letter of any of the names. Then the answer to the problem is the product of <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> is a number of different letters in the names placed in position <span class=\"tex-span\"><i>i</i></span>.</p><h4><a href=\"/contest/152/problem/D\" title=\"Codeforces Round 108 (Div. 2)\">152D - Frames</a></h4><p>It was necessary to understand if there are two borders or not.</p><p>Let's distinguish those <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates, in which there are at least <span class=\"tex-span\">3</span> consecutive symbols '#', becouse the length of each border is no less then <span class=\"tex-span\">3</span>. It is clear that the coordinates of the corners of borders should be chosen only from those selected <span class=\"tex-span\"><i>x</i></span> and <span class=\"tex-span\"><i>y</i></span>. In general, the various selected <span class=\"tex-span\"><i>x</i></span> no more then <span class=\"tex-span\">4</span> and various selected <span class=\"tex-span\"><i>y</i></span> no more then <span class=\"tex-span\">4</span>.</p><p>Except that case when the height or width of the first border is <span class=\"tex-span\">3</span>, and length of the second side of this border is more than <span class=\"tex-span\">3</span>, and one side of the second border fills a part of the inside first at least.</p><p>For example:</p> <pre>#######\n#######\n#######\n#.....#\n#######</pre><p>The first border:</p> <pre>#######\n#.....#\n#######\n.......\n.......</pre><p>The second border:</p> <pre>.......\n#######\n#.....#\n#.....#\n#######</pre><p>There are <span class=\"tex-span\">7</span> different <span class=\"tex-span\"><i>y</i></span>-coordinates in the example.</p><p>Carefully processed these cases separately, it is quite simple. (Let's choose <span class=\"tex-span\">4</span> <span class=\"tex-span\"><i>y</i></span>-coordinates: minimum, maximum, second minimum and second maximum).</p><p>Otherwise, if the amount selected <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates no more then <span class=\"tex-span\">4</span>, then let's choose opposite corners of the first and second borders and verify that the selected borders — the correct borders and there are no other characters '#'. Checking is carried out at <span class=\"tex-span\"><i>O</i>(<i>n</i> + <i>m</i>)</span> or <span class=\"tex-span\"><i>O</i>(1)</span> (using partial sums).</p><h4><a href=\"/contest/152/problem/E\" title=\"Codeforces Round 108 (Div. 2)\">152E - Garden</a></h4><p>The solution of this problem is based on dynamic programming. <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> — the value of the minimum correct concrete cover, if we consider as important elements only elements of the mask <span class=\"tex-span\"><i>mask</i></span>, and there are additionally covered the vertex <span class=\"tex-span\"><i>v</i> = (<i>i</i>, <i>j</i>)</span> of the field.</p><p>There are two types of transfers.</p><p>First of all we can, as if to cut coverage on the vertex <span class=\"tex-span\"><i>v</i></span>. Then you need to go through subpattern of vertex <span class=\"tex-span\"><i>submask</i></span>, which will go to the left coverage and make an optimizing transfer. Update <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> with the value <span class=\"tex-span\"><i>dp</i>[<i>submask</i>][<i>v</i>] + <i>dp</i>[<i>mask</i> ^ <i>submask</i>][<i>v</i>] - <i>cost</i>(<i>v</i>)</span>.</p><p>Second, perhaps in the vertex <span class=\"tex-span\"><i>v</i></span> in the optimal coverage mask <span class=\"tex-span\"><i>mask</i></span>, which covers the vertex <span class=\"tex-span\"><i>v</i></span>, you can not make the cut separating the set of vertices. In this case, this vertex forms something a kind of <>. And there a vertex <span class=\"tex-span\"><i>u</i></span> exists, on which we can make the cut, with the whole shortest path from a vertex <span class=\"tex-span\"><i>u</i></span> to <span class=\"tex-span\"><i>v</i></span> belongs to the optimal coverage. Let's precalculate the shortest paths between all pairs of cells. Now to make this transition, we should count the value of dynamics <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> for all vertices <span class=\"tex-span\"><i>v</i></span> only on the basis of the first transition. Now you can make the second transition. For all <span class=\"tex-span\"><i>u</i></span>, <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span>, update the value of <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>u</i>] + <i>dist</i>(<i>v</i>, <i>u</i>) - <i>cost</i>(<i>u</i>)</span>.</p><p>Let's process separately state in which exactly one bit in the mask, and the vertex which corresponding to this bit is equal to <span class=\"tex-span\"><i>v</i></span>. In this case the answer is equal to <span class=\"tex-span\"><i>cost</i>(<i>v</i>)</span>, of course.</p><p>Thus, each solution is obtained for the <span class=\"tex-span\"><i>O</i>(<i>min</i>(3<sup class=\"upper-index\"><i>k</i></sup>·<i>n</i>·<i>m</i>, 2<sup class=\"upper-index\"><i>k</i></sup>·(<i>n</i>·<i>m</i>)<sup class=\"upper-index\">2</sup>))</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/152\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 108 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-795-3940\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"795\",\n blogEntryId: \"3926\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=div+2\" class=\"tag notice\" style=\"text-decoration: none;\">div 2</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=editorial\" class=\"tag notice\" style=\"text-decoration: none;\">editorial</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+30</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Gerald\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Gerald\">\n Gerald\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3926#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3926#comments\">\n 26\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3950\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (15)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79734\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Acko\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4578/avatar/98a7ec7b1cb1a249.jpg'/> </a>\n <div><a href=\"/profile/Acko\" title=\"Candidate Master Acko\" class=\"rated-user user-violet\">Acko</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 02:07\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79734\" href=\"?#comment-79734\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79734\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4578\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79734\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was wondering if this idea is correct for task E ( I passed pretest in the competition but received WA10 at system test ). For each field of the matrix I run Dijkstra's algorithm with that field as source where cost ( u, v ) = Field[v] ( u and v are pairs of integers ). Then I reconstruct each paths from each of K important nodes to source and check if I have min path. Can you give me an example for which my idea fails or send me test #10. Thank you. :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79734 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79734 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79734\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79738\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/peking2\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/peking2\" title=\"Specialist peking2\" class=\"rated-user user-cyan\">peking2</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 04:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79738\" href=\"?#comment-79738\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79738\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"42638\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79738\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>First time to write Dijkstra for task E, but it seems not the correct solution. Overall solution is not necessary to be shortest path for each pair. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79738 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79738 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79738\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79741\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 06:25\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79741\" href=\"?#comment-79741\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79741\" revisionCount=\"5\" revision=\"5\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">5</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79741\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79741\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also have a solution similar to what they mentioned but a little different.<br />I try the following for each of the k! permutations of important nodes:</p><p>S={1stnode}<br />foreach i=2:k<br />1) Get shortest path between i and any of the nodes in S<br />2) Add cost of that path to total cost<br />3) Add nodes in that path to S<br />Minimize over all permutations.<br />It fails at test case 19 which is pretty large so I can even see fully. Can someone tell me what's wrong with the solution?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79741 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79741 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79741\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79761\" commentParentId=\"79741\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/coolinging\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/17136/avatar/8eebbd02d2734be7.jpg'/> </a>\n <div><a href=\"/profile/coolinging\" title=\"Master coolinging\" class=\"rated-user user-orange\">coolinging</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 10:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79761\" href=\"?#comment-79761\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79741\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79761\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79761\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"17136\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79761\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is a simple 3*3 example(1 are important squares):</p><p>2 1 2</p><p>1 6 1</p><p>2 1 2</p><p>The answer is: </p><p>10</p><p>.X.</p><p>XXX</p><p>.X.</p><p>Your solution's ans:</p><p>12</p><p>XXX</p><p>X.X</p><p>XXX</p><p>Some nodes are useless if there are only 2 important squares(Only nodes in the shortest path is useful),but useful if there are many important squares. (Just think the square 6 above.It isn't in the shortest path of any pair important squares,but it's benefit for all the important squares.) So considering only one node each time is incorrect.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79761 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79761 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79761\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79765\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 12:23\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79765\" href=\"?#comment-79765\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79765\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79765\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I see your point. Thanks a lot :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79765 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79765 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79765\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79793\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/dorellin\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/20026/avatar/9ab45d22868e4b56.jpg'/> </a>\n <div><a href=\"/profile/dorellin\" title=\"Candidate Master dorellin\" class=\"rated-user user-violet\">dorellin</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 19:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79793\" href=\"?#comment-79793\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79793\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"20026\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79793\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I tried this approach of minimization over all permutations of the k important nodes by doing the following:</p><p>for each permutation </p><p>i from 1:K-1:</p><p>calculate the sortest path from i to i+1 </p><p>all grid positions along the shortest path are reseted to 0</p><p>reset the grid to original after each permutation</p><p>gets WA on test case 10. I wonder if this idea is simply wrong. By the way, it works for the sample given by coolingging. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79793 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79793 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79793\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79745\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Oi.\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Oi.\" title=\"Expert Oi.\" class=\"rated-user user-blue\">Oi.</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 07:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79745\" href=\"?#comment-79745\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79745\" revisionCount=\"12\" revision=\"12\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">12</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79745\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"7\"\r\n data-commentUserId=\"8777\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+7</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79745\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I must confess I was a bit surprised at the "almost binary search" suggestion for problem B. You can just do straight divisions to check the maximum amount of steps possible!</p> <pre><code>if(dx > 0) ans = (n-xc)/dx;\nif(dx < 0) ans = (xc-1)/-dx;\nif(dy > 0) ans = min(ans, (m-yc)/dy);\nif(dy < 0) ans = min(ans, (yc-1)/-dy);\nxc += dx*ans;\nyc += dy*ans;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79745 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79745 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79745\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79749\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/NRCover\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/6450/avatar/bb89f3d49558861e.jpg'/> </a>\n <div><a href=\"/profile/NRCover\" title=\"Candidate Master NRCover\" class=\"rated-user user-violet\">NRCover</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 08:42\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79749\" href=\"?#comment-79749\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79749\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79749\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"24\"\r\n data-commentUserId=\"6450\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+24</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79749\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem E is a good problem. I feel that i learned a lot. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79749 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79749 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79749\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79823\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/CMH\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/CMH\" title=\"Expert CMH\" class=\"rated-user user-blue\">CMH</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/22/2012 07:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79823\" href=\"?#comment-79823\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79823\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"6\"\r\n data-commentUserId=\"39979\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+6</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79823\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think that E is a very good state of the compressed DP problem,and It is very similar with the 2008 Chinese Informatics Olympiad winter camp's test of trip ( tour plan ).I think tha they are all good.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79823 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79823 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79823\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80181\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/looool\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/looool\" title=\"Specialist looool\" class=\"rated-user user-cyan\">looool</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/25/2012 15:44\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80181\" href=\"?#comment-80181\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80181\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"25841\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80181\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can someone tell what's the meaning of "name number 1" in problem statement C -> <a href=\"//codeforces.com/contest/152/problem/C\"></a><a href=\"//codeforces.com/contest/152/problem/C\">Link</a></p><p>I will be grateful.</p><p>Thanks.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80181 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80181 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80181\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219284\" commentParentId=\"80181\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/25/2015 22:29\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219284\" href=\"?#comment-219284\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80181\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219284\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219284\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also can't get the idea!! Since we are swapping prefix and i & j should be >=1 & <=n. thats a problem for me!! Is this possible that, After swapping I've got a new word then I can also perform swap operation on this?? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219284 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219284 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219284\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219317\" commentParentId=\"219284\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/26/2015 08:56\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219317\" href=\"?#comment-219317\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-219284\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219317\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219317\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yes!! I've got it in my manner. Suppose, you have ABC & DEF .. then the possible different names are ABC,DEF,AEF,DBF,ABF,DEC,AEC,DBC=8 . Go with some example in paper.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219317 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219317 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219317\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"231780\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/sidhant\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/221909/avatar/8436b81921273f4.jpg'/> </a>\n <div><a href=\"/profile/sidhant\" title=\"Master sidhant\" class=\"rated-user user-orange\">sidhant</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/01/2015 18:17\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-231780\" href=\"?#comment-231780\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"231780\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"221909\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-231780\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Could anyone please give a more elaborate explanation of the solution of problem E.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-231780 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-231780 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-231780\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"295095\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shubhamgoyal__\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/shubhamgoyal__\" title=\"Candidate Master shubhamgoyal__\" class=\"rated-user user-violet\">shubhamgoyal__</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"May/20/2016 14:17\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-295095\" href=\"?#comment-295095\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"295095\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"321533\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-295095\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can somebody plz explain what does v represent in dp[mask][v] as explained in the editorial of Question E Garden</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-295095 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-295095 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-295095\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"954930\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nskybytskyi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/575628/avatar/e06ecd9e59495e05.jpg'/> </a>\n <div><a href=\"/profile/nskybytskyi\" title=\"International Master nskybytskyi\" class=\"rated-user user-orange\">nskybytskyi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/21/2022 17:26\">13 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-954930\" href=\"?#comment-954930\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"954930\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"575628\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-954930\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In the complexity analysis of problem E, you forgot to account for all pairs' shortest paths precomputation. Usually one would use Floyd-Warshall for APSP with a complexity of $$$O((n \\cdot m)^3)$$$. However, the graph in this problem is sparse with $$$|E| \\le 4 |V|$$$, making a series of $$$O(|V|)$$$ Dijkstras another viable solution with the overall complexity of $$$O((n \\cdot m)^2 \\log (n \\cdot m))$$$.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-954930 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-954930 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-954930\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3950\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 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Garden"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Garden</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya has a very beautiful country garden that can be represented as an <span class=\"tex-span\"><i>n</i> × <i>m</i></span> rectangular field divided into <span class=\"tex-span\"><i>n</i>·<i>m</i></span> squares. One beautiful day Vasya remembered that he needs to pave roads between <span class=\"tex-span\"><i>k</i></span> important squares that contain buildings. To pave a road, he can cover some squares of his garden with concrete.</p><p>For each garden square we know number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub></span> that represents the number of flowers that grow in the square with coordinates <span class=\"tex-span\">(<i>i</i>, <i>j</i>)</span>. When a square is covered with concrete, all flowers that grow in the square die.</p><p>Vasya wants to cover some squares with concrete so that the following conditions were fulfilled: </p><ul> <li> all <span class=\"tex-span\"><i>k</i></span> important squares should necessarily be covered with concrete </li><li> from each important square there should be a way to any other important square. The way should go be paved with concrete-covered squares considering that neighboring squares are squares that have a common side </li><li> the total number of dead plants should be minimum </li></ul><p>As Vasya has a rather large garden, he asks you to help him.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>, <span class=\"tex-span\"><i>n</i>·<i>m</i> ≤ 200</span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>min</i>(<i>n</i>·<i>m</i>, 7</span>)) — the garden's sizes and the number of the important squares. Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains <span class=\"tex-span\"><i>m</i></span> numbers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub> ≤ 1000</span>) — the numbers of flowers in the squares. Next <span class=\"tex-span\"><i>k</i></span> lines contain coordinates of important squares written as \"<span class=\"tex-span\"><i>x</i></span> <span class=\"tex-span\"><i>y</i></span>\" (without quotes) (<span class=\"tex-span\">1 ≤ <i>x</i> ≤ <i>n</i></span>, <span class=\"tex-span\">1 ≤ <i>y</i> ≤ <i>m</i></span>). The numbers written on one line are separated by spaces. It is guaranteed that all <span class=\"tex-span\"><i>k</i></span> important squares have different coordinates.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the single integer — the minimum number of plants that die during the road construction. Then print <span class=\"tex-span\"><i>n</i></span> lines each containing <span class=\"tex-span\"><i>m</i></span> characters — the garden's plan. In this plan use character \"<span class=\"tex-font-style-tt\">X</span>\" (uppercase Latin letter X) to represent a concrete-covered square and use character \".\" (dot) for a square that isn't covered with concrete. If there are multiple solutions, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 2<br/>1 2 3<br/>1 2 3<br/>1 2 3<br/>1 2<br/>3 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br/>.X.<br/>.X.<br/>.XX<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5 4<br/>1 4 5 1 2<br/>2 2 2 2 7<br/>2 4 1 4 5<br/>3 2 1 7 1<br/>1 1<br/>1 5<br/>4 1<br/>4 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>26<br/>X..XX<br/>XXXX.<br/>X.X..<br/>X.XX.<br/></pre></div></div></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"cf7d7536f4594c2ec6cf51c0db4873a1\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"07df7ea636cdbe445e0517a615206bf83136675b\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/152\">Codeforces Round 108 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='cf7d7536f4594c2ec6cf51c0db4873a1'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/152/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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}\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"E\" data-uuid=\"ps_016c7e36db5fbece2847d6c300e72759be8cae95\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Garden</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya has a very beautiful country garden that can be represented as an <span class=\"tex-span\"><i>n</i> × <i>m</i></span> rectangular field divided into <span class=\"tex-span\"><i>n</i>·<i>m</i></span> squares. One beautiful day Vasya remembered that he needs to pave roads between <span class=\"tex-span\"><i>k</i></span> important squares that contain buildings. To pave a road, he can cover some squares of his garden with concrete.</p><p>For each garden square we know number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub></span> that represents the number of flowers that grow in the square with coordinates <span class=\"tex-span\">(<i>i</i>, <i>j</i>)</span>. When a square is covered with concrete, all flowers that grow in the square die.</p><p>Vasya wants to cover some squares with concrete so that the following conditions were fulfilled: </p><ul> <li> all <span class=\"tex-span\"><i>k</i></span> important squares should necessarily be covered with concrete </li><li> from each important square there should be a way to any other important square. The way should go be paved with concrete-covered squares considering that neighboring squares are squares that have a common side </li><li> the total number of dead plants should be minimum </li></ul><p>As Vasya has a rather large garden, he asks you to help him.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains three integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>m</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 100</span>, <span class=\"tex-span\"><i>n</i>·<i>m</i> ≤ 200</span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>min</i>(<i>n</i>·<i>m</i>, 7</span>)) — the garden's sizes and the number of the important squares. Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains <span class=\"tex-span\"><i>m</i></span> numbers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub><sub class=\"lower-index\"><i>j</i></sub> ≤ 1000</span>) — the numbers of flowers in the squares. Next <span class=\"tex-span\"><i>k</i></span> lines contain coordinates of important squares written as "<span class=\"tex-span\"><i>x</i></span> <span class=\"tex-span\"><i>y</i></span>" (without quotes) (<span class=\"tex-span\">1 ≤ <i>x</i> ≤ <i>n</i></span>, <span class=\"tex-span\">1 ≤ <i>y</i> ≤ <i>m</i></span>). The numbers written on one line are separated by spaces. It is guaranteed that all <span class=\"tex-span\"><i>k</i></span> important squares have different coordinates.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print the single integer — the minimum number of plants that die during the road construction. Then print <span class=\"tex-span\"><i>n</i></span> lines each containing <span class=\"tex-span\"><i>m</i></span> characters — the garden's plan. In this plan use character "<span class=\"tex-font-style-tt\">X</span>" (uppercase Latin letter X) to represent a concrete-covered square and use character "." (dot) for a square that isn't covered with concrete. If there are multiple solutions, print any of them.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3 2<br />1 2 3<br />1 2 3<br />1 2 3<br />1 2<br />3 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br />.X.<br />.X.<br />.XX<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5 4<br />1 4 5 1 2<br />2 2 2 2 7<br />2 4 1 4 5<br />3 2 1 7 1<br />1 1<br />1 5<br />4 1<br />4 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>26<br />X..XX<br />XXXX.<br />X.X..<br />X.XX.<br /></pre></div></div></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=E]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f898c2ea37ea4fba4315ca79ae6e074b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Gerald\">Gerald</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Gerald\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Gerald\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Gerald\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Gerald\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Gerald\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Gerald\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Gerald\" style=\"text-decoration:none;color:black !important;\">Gerald's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3940\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3926\"> <p>Разбор задач Codeforces Round #108 (Div. 2) </p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Gerald\" title=\"Master Gerald\" class=\"rated-user user-orange\">Gerald</a>,\r\n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h4><a href=\"/contest/152/problem/A\" title=\"Codeforces Round 108 (Div. 2)\">152A - Marks</a></h4><p>In this problem you should do exactly what is written in the statement. Here is rough code of solution:</p> <pre><code>for (int i = 0; i < n; ++i){ \n bool wasBest = false;\n for(int j = 0; j < m; ++j){\n bool isBest = true;\n for(int k = 0; k < n; ++k)\n if(a[k][j] > a[i][j])\n isBest = false;\n if(isBest) \n wasBest = true;\n }\n if(wasBest)\n ans++;\n} \n</code></pre><h4><a href=\"/contest/152/problem/B\" title=\"Codeforces Round 108 (Div. 2)\">152B - Steps</a></h4><p>Let's find a formula for the position <span class=\"tex-span\">(<i>x</i>, <i>y</i>)</span> and vector <span class=\"tex-span\">(<i>dx</i>, <i>dy</i>)</span>, how many steps to stop the boy can do. You should use "almost" binary search, for example, see the code written by <a class=\"rated-user user-violet\" href=\"/profile/RAD\" title=\"Candidate Master RAD\">RAD</a>.</p> <pre><code>for (long long cof = 1100000000; cof; cof /= 2)\n while (onField(xc + cof * dx, yc + cof * dy)) {\n xc = xc + cof * dx;\n yc = yc + cof * dy;\n ans += cof;\n } \n</code></pre><h4><a href=\"/contest/152/problem/C\" title=\"Codeforces Round 108 (Div. 2)\">152C - Pocket Book</a></h4><p>In this task, it was necessary to understand that in position <span class=\"tex-span\">1</span> Vasya can get any name of a special form. More exactly, it's the name of form <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">3</sub></span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">4</sub></span> <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span>, where <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub></span> — the first letter of any of the names, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">2</sub></span> — the second letter of any of the names, <span class=\"tex-span\">...</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>m</i></sub></span> — <span class=\"tex-span\"><i>m</i></span>-th letter of any of the names. Then the answer to the problem is the product of <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>m</i></span>), where <span class=\"tex-span\"><i>cnt</i><sub class=\"lower-index\"><i>i</i></sub></span> is a number of different letters in the names placed in position <span class=\"tex-span\"><i>i</i></span>.</p><h4><a href=\"/contest/152/problem/D\" title=\"Codeforces Round 108 (Div. 2)\">152D - Frames</a></h4><p>It was necessary to understand if there are two borders or not.</p><p>Let's distinguish those <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates, in which there are at least <span class=\"tex-span\">3</span> consecutive symbols '#', becouse the length of each border is no less then <span class=\"tex-span\">3</span>. It is clear that the coordinates of the corners of borders should be chosen only from those selected <span class=\"tex-span\"><i>x</i></span> and <span class=\"tex-span\"><i>y</i></span>. In general, the various selected <span class=\"tex-span\"><i>x</i></span> no more then <span class=\"tex-span\">4</span> and various selected <span class=\"tex-span\"><i>y</i></span> no more then <span class=\"tex-span\">4</span>.</p><p>Except that case when the height or width of the first border is <span class=\"tex-span\">3</span>, and length of the second side of this border is more than <span class=\"tex-span\">3</span>, and one side of the second border fills a part of the inside first at least.</p><p>For example:</p> <pre>#######\n#######\n#######\n#.....#\n#######</pre><p>The first border:</p> <pre>#######\n#.....#\n#######\n.......\n.......</pre><p>The second border:</p> <pre>.......\n#######\n#.....#\n#.....#\n#######</pre><p>There are <span class=\"tex-span\">7</span> different <span class=\"tex-span\"><i>y</i></span>-coordinates in the example.</p><p>Carefully processed these cases separately, it is quite simple. (Let's choose <span class=\"tex-span\">4</span> <span class=\"tex-span\"><i>y</i></span>-coordinates: minimum, maximum, second minimum and second maximum).</p><p>Otherwise, if the amount selected <span class=\"tex-span\"><i>x</i></span> — and <span class=\"tex-span\"><i>y</i></span>-coordinates no more then <span class=\"tex-span\">4</span>, then let's choose opposite corners of the first and second borders and verify that the selected borders — the correct borders and there are no other characters '#'. Checking is carried out at <span class=\"tex-span\"><i>O</i>(<i>n</i> + <i>m</i>)</span> or <span class=\"tex-span\"><i>O</i>(1)</span> (using partial sums).</p><h4><a href=\"/contest/152/problem/E\" title=\"Codeforces Round 108 (Div. 2)\">152E - Garden</a></h4><p>The solution of this problem is based on dynamic programming. <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> — the value of the minimum correct concrete cover, if we consider as important elements only elements of the mask <span class=\"tex-span\"><i>mask</i></span>, and there are additionally covered the vertex <span class=\"tex-span\"><i>v</i> = (<i>i</i>, <i>j</i>)</span> of the field.</p><p>There are two types of transfers.</p><p>First of all we can, as if to cut coverage on the vertex <span class=\"tex-span\"><i>v</i></span>. Then you need to go through subpattern of vertex <span class=\"tex-span\"><i>submask</i></span>, which will go to the left coverage and make an optimizing transfer. Update <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> with the value <span class=\"tex-span\"><i>dp</i>[<i>submask</i>][<i>v</i>] + <i>dp</i>[<i>mask</i> ^ <i>submask</i>][<i>v</i>] - <i>cost</i>(<i>v</i>)</span>.</p><p>Second, perhaps in the vertex <span class=\"tex-span\"><i>v</i></span> in the optimal coverage mask <span class=\"tex-span\"><i>mask</i></span>, which covers the vertex <span class=\"tex-span\"><i>v</i></span>, you can not make the cut separating the set of vertices. In this case, this vertex forms something a kind of <>. And there a vertex <span class=\"tex-span\"><i>u</i></span> exists, on which we can make the cut, with the whole shortest path from a vertex <span class=\"tex-span\"><i>u</i></span> to <span class=\"tex-span\"><i>v</i></span> belongs to the optimal coverage. Let's precalculate the shortest paths between all pairs of cells. Now to make this transition, we should count the value of dynamics <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span> for all vertices <span class=\"tex-span\"><i>v</i></span> only on the basis of the first transition. Now you can make the second transition. For all <span class=\"tex-span\"><i>u</i></span>, <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>v</i>]</span>, update the value of <span class=\"tex-span\"><i>dp</i>[<i>mask</i>][<i>u</i>] + <i>dist</i>(<i>v</i>, <i>u</i>) - <i>cost</i>(<i>u</i>)</span>.</p><p>Let's process separately state in which exactly one bit in the mask, and the vertex which corresponding to this bit is equal to <span class=\"tex-span\"><i>v</i></span>. In this case the answer is equal to <span class=\"tex-span\"><i>cost</i>(<i>v</i>)</span>, of course.</p><p>Thus, each solution is obtained for the <span class=\"tex-span\"><i>O</i>(<i>min</i>(3<sup class=\"upper-index\"><i>k</i></sup>·<i>n</i>·<i>m</i>, 2<sup class=\"upper-index\"><i>k</i></sup>·(<i>n</i>·<i>m</i>)<sup class=\"upper-index\">2</sup>))</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/152\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 108 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-795-3940\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"795\",\n blogEntryId: \"3926\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=div+2\" class=\"tag notice\" style=\"text-decoration: none;\">div 2</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=editorial\" class=\"tag notice\" style=\"text-decoration: none;\">editorial</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+30</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3940\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Gerald\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Gerald\">\n Gerald\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/20/2012 21:39\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3926#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3926#comments\">\n 26\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3950\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (15)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79734\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Acko\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/4578/avatar/98a7ec7b1cb1a249.jpg'/> </a>\n <div><a href=\"/profile/Acko\" title=\"Candidate Master Acko\" class=\"rated-user user-violet\">Acko</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 02:07\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79734\" href=\"?#comment-79734\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79734\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4578\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79734\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was wondering if this idea is correct for task E ( I passed pretest in the competition but received WA10 at system test ). For each field of the matrix I run Dijkstra's algorithm with that field as source where cost ( u, v ) = Field[v] ( u and v are pairs of integers ). Then I reconstruct each paths from each of K important nodes to source and check if I have min path. Can you give me an example for which my idea fails or send me test #10. Thank you. :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79734 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79734 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79734\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79738\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/peking2\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/peking2\" title=\"Specialist peking2\" class=\"rated-user user-cyan\">peking2</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 04:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79738\" href=\"?#comment-79738\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79738\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"42638\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79738\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>First time to write Dijkstra for task E, but it seems not the correct solution. Overall solution is not necessary to be shortest path for each pair. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79738 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79738 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79738\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79741\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 06:25\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79741\" href=\"?#comment-79741\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79741\" revisionCount=\"5\" revision=\"5\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">5</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79741\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79741\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also have a solution similar to what they mentioned but a little different.<br />I try the following for each of the k! permutations of important nodes:</p><p>S={1stnode}<br />foreach i=2:k<br />1) Get shortest path between i and any of the nodes in S<br />2) Add cost of that path to total cost<br />3) Add nodes in that path to S<br />Minimize over all permutations.<br />It fails at test case 19 which is pretty large so I can even see fully. Can someone tell me what's wrong with the solution?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79741 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79741 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79741\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79761\" commentParentId=\"79741\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/coolinging\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/17136/avatar/8eebbd02d2734be7.jpg'/> </a>\n <div><a href=\"/profile/coolinging\" title=\"Master coolinging\" class=\"rated-user user-orange\">coolinging</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 10:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79761\" href=\"?#comment-79761\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79741\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79761\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79761\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"17136\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79761\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is a simple 3*3 example(1 are important squares):</p><p>2 1 2</p><p>1 6 1</p><p>2 1 2</p><p>The answer is: </p><p>10</p><p>.X.</p><p>XXX</p><p>.X.</p><p>Your solution's ans:</p><p>12</p><p>XXX</p><p>X.X</p><p>XXX</p><p>Some nodes are useless if there are only 2 important squares(Only nodes in the shortest path is useful),but useful if there are many important squares. (Just think the square 6 above.It isn't in the shortest path of any pair important squares,but it's benefit for all the important squares.) So considering only one node each time is incorrect.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79761 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79761 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79761\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79765\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/islam-al-aarag\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/islam-al-aarag\" title=\"Master islam-al-aarag\" class=\"rated-user user-orange\">islam-al-aarag</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 12:23\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79765\" href=\"?#comment-79765\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79765\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1967\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79765\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I see your point. Thanks a lot :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79765 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79765 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79765\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79793\" commentParentId=\"79761\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/dorellin\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/20026/avatar/9ab45d22868e4b56.jpg'/> </a>\n <div><a href=\"/profile/dorellin\" title=\"Candidate Master dorellin\" class=\"rated-user user-violet\">dorellin</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 19:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79793\" href=\"?#comment-79793\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-79761\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79793\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"20026\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79793\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I tried this approach of minimization over all permutations of the k important nodes by doing the following:</p><p>for each permutation </p><p>i from 1:K-1:</p><p>calculate the sortest path from i to i+1 </p><p>all grid positions along the shortest path are reseted to 0</p><p>reset the grid to original after each permutation</p><p>gets WA on test case 10. I wonder if this idea is simply wrong. By the way, it works for the sample given by coolingging. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79793 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79793 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79793\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79745\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Oi.\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Oi.\" title=\"Expert Oi.\" class=\"rated-user user-blue\">Oi.</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 07:51\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79745\" href=\"?#comment-79745\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79745\" revisionCount=\"12\" revision=\"12\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">12</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79745\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"7\"\r\n data-commentUserId=\"8777\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+7</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79745\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I must confess I was a bit surprised at the "almost binary search" suggestion for problem B. You can just do straight divisions to check the maximum amount of steps possible!</p> <pre><code>if(dx > 0) ans = (n-xc)/dx;\nif(dx < 0) ans = (xc-1)/-dx;\nif(dy > 0) ans = min(ans, (m-yc)/dy);\nif(dy < 0) ans = min(ans, (yc-1)/-dy);\nxc += dx*ans;\nyc += dy*ans;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79745 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79745 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79745\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79749\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/NRCover\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/6450/avatar/bb89f3d49558861e.jpg'/> </a>\n <div><a href=\"/profile/NRCover\" title=\"Candidate Master NRCover\" class=\"rated-user user-violet\">NRCover</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/21/2012 08:42\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79749\" href=\"?#comment-79749\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"79749\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"79749\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"24\"\r\n data-commentUserId=\"6450\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+24</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79749\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem E is a good problem. I feel that i learned a lot. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79749 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79749 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79749\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"79823\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/CMH\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/CMH\" title=\"Expert CMH\" class=\"rated-user user-blue\">CMH</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/22/2012 07:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-79823\" href=\"?#comment-79823\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"79823\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"6\"\r\n data-commentUserId=\"39979\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+6</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-79823\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think that E is a very good state of the compressed DP problem,and It is very similar with the 2008 Chinese Informatics Olympiad winter camp's test of trip ( tour plan ).I think tha they are all good.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-79823 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-79823 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-79823\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80181\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/looool\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/looool\" title=\"Specialist looool\" class=\"rated-user user-cyan\">looool</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/25/2012 15:44\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80181\" href=\"?#comment-80181\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80181\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"25841\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80181\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can someone tell what's the meaning of "name number 1" in problem statement C -> <a href=\"//codeforces.com/contest/152/problem/C\"></a><a href=\"//codeforces.com/contest/152/problem/C\">Link</a></p><p>I will be grateful.</p><p>Thanks.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80181 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80181 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80181\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219284\" commentParentId=\"80181\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/25/2015 22:29\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219284\" href=\"?#comment-219284\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80181\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219284\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219284\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also can't get the idea!! Since we are swapping prefix and i & j should be >=1 & <=n. thats a problem for me!! Is this possible that, After swapping I've got a new word then I can also perform swap operation on this?? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219284 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219284 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219284\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"219317\" commentParentId=\"219284\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Jahid\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/99667/avatar/700f1e2c8b76be17.jpg'/> </a>\n <div><a href=\"/profile/Jahid\" title=\"Pupil Jahid\" class=\"rated-user user-green\">Jahid</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/26/2015 08:56\">9 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-219317\" href=\"?#comment-219317\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-219284\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"219317\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"99667\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-219317\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yes!! I've got it in my manner. Suppose, you have ABC & DEF .. then the possible different names are ABC,DEF,AEF,DBF,ABF,DEC,AEC,DBC=8 . Go with some example in paper.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-219317 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-219317 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-219317\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"231780\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/sidhant\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/221909/avatar/8436b81921273f4.jpg'/> </a>\n <div><a href=\"/profile/sidhant\" title=\"Master sidhant\" class=\"rated-user user-orange\">sidhant</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jun/01/2015 18:17\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-231780\" href=\"?#comment-231780\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"231780\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"221909\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-231780\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Could anyone please give a more elaborate explanation of the solution of problem E.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-231780 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-231780 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-231780\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"295095\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shubhamgoyal__\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/shubhamgoyal__\" title=\"Candidate Master shubhamgoyal__\" class=\"rated-user user-violet\">shubhamgoyal__</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"May/20/2016 14:17\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-295095\" href=\"?#comment-295095\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"295095\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"321533\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-295095\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can somebody plz explain what does v represent in dp[mask][v] as explained in the editorial of Question E Garden</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-295095 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-295095 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-295095\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"954930\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nskybytskyi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/575628/avatar/e06ecd9e59495e05.jpg'/> </a>\n <div><a href=\"/profile/nskybytskyi\" title=\"International Master nskybytskyi\" class=\"rated-user user-orange\">nskybytskyi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Sep/21/2022 17:26\">13 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-954930\" href=\"?#comment-954930\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"954930\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"9\"\r\n data-commentUserId=\"575628\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+9</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-954930\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In the complexity analysis of problem E, you forgot to account for all pairs' shortest paths precomputation. Usually one would use Floyd-Warshall for APSP with a complexity of $$$O((n \\cdot m)^3)$$$. However, the graph in this problem is sparse with $$$|E| \\le 4 |V|$$$, making a series of $$$O(|V|)$$$ Dijkstras another viable solution with the overall complexity of $$$O((n \\cdot m)^2 \\log (n \\cdot m))$$$.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-954930 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-954930 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-954930\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3950\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 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Hometask"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Hometask</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sergey attends lessons of the <span class=\"tex-span\"><i>N</i></span>-ish language. Each lesson he receives a hometask. This time the task is to translate some sentence to the <span class=\"tex-span\"><i>N</i></span>-ish language. Sentences of the <span class=\"tex-span\"><i>N</i></span>-ish language can be represented as strings consisting of lowercase Latin letters without spaces or punctuation marks.</p><p>Sergey totally forgot about the task until half an hour before the next lesson and hastily scribbled something down. But then he recollected that in the last lesson he learned the grammar of <span class=\"tex-span\"><i>N</i></span>-ish. The spelling rules state that <span class=\"tex-span\"><i>N</i></span>-ish contains some \"forbidden\" pairs of letters: such letters can never occur in a sentence next to each other. Also, the order of the letters doesn't matter (for example, if the pair of letters \"<span class=\"tex-font-style-tt\">ab</span>\" is forbidden, then any occurrences of substrings \"<span class=\"tex-font-style-tt\">ab</span>\" and \"<span class=\"tex-font-style-tt\">ba</span>\" are also forbidden). Also, each pair has different letters and each letter occurs in no more than one forbidden pair.</p><p>Now Sergey wants to correct his sentence so that it doesn't contain any \"forbidden\" pairs of letters that stand next to each other. However, he is running out of time, so he decided to simply cross out some letters from the sentence. What smallest number of letters will he have to cross out? When a letter is crossed out, it is \"removed\" so that the letters to its left and right (if they existed), become neighboring. For example, if we cross out the first letter from the string \"<span class=\"tex-font-style-tt\">aba</span>\", we get the string \"<span class=\"tex-font-style-tt\">ba</span>\", and if we cross out the second letter, we get \"<span class=\"tex-font-style-tt\">aa</span>\".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters — that's the initial sentence in <span class=\"tex-span\"><i>N</i></span>-ish, written by Sergey. The length of string <span class=\"tex-span\"><i>s</i></span> doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\">5</sup></span>.</p><p>The next line contains integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ 13</span>) — the number of forbidden pairs of letters.</p><p>Next <span class=\"tex-span\"><i>k</i></span> lines contain descriptions of forbidden pairs of letters. Each line contains exactly two different lowercase Latin letters without separators that represent the forbidden pairs. It is guaranteed that each letter is included in no more than one pair.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the smallest number of letters that need to be removed to get a string without any forbidden pairs of neighboring letters. Please note that the answer always exists as it is always possible to remove all letters.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>ababa<br/>1<br/>ab<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>codeforces<br/>2<br/>do<br/>cs<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you should remove two letters <span class=\"tex-font-style-tt\">b</span>.</p><p>In the second sample you should remove the second or the third letter. 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Greedy algorithms\">\r\n greedy\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *1600\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='770fe510a3a574c499e3146f92224fdd'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"954\"/>\r\n <input name=\"tagName\" type=\"hidden\" 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href=\"/blog/entry/3958\" title=\"Codeforces Round #109\" target=\"_blank\">Codeforces Round #109</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"994:995\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3969\" title=\"Codeforces Round #109: editorial\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"996:997\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" 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const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_3273fc75585ec4b8f0152878c996cb23a5cdbbac\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Hometask</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sergey attends lessons of the <span class=\"tex-span\"><i>N</i></span>-ish language. Each lesson he receives a hometask. This time the task is to translate some sentence to the <span class=\"tex-span\"><i>N</i></span>-ish language. Sentences of the <span class=\"tex-span\"><i>N</i></span>-ish language can be represented as strings consisting of lowercase Latin letters without spaces or punctuation marks.</p><p>Sergey totally forgot about the task until half an hour before the next lesson and hastily scribbled something down. But then he recollected that in the last lesson he learned the grammar of <span class=\"tex-span\"><i>N</i></span>-ish. The spelling rules state that <span class=\"tex-span\"><i>N</i></span>-ish contains some "forbidden" pairs of letters: such letters can never occur in a sentence next to each other. Also, the order of the letters doesn't matter (for example, if the pair of letters "<span class=\"tex-font-style-tt\">ab</span>" is forbidden, then any occurrences of substrings "<span class=\"tex-font-style-tt\">ab</span>" and "<span class=\"tex-font-style-tt\">ba</span>" are also forbidden). Also, each pair has different letters and each letter occurs in no more than one forbidden pair.</p><p>Now Sergey wants to correct his sentence so that it doesn't contain any "forbidden" pairs of letters that stand next to each other. However, he is running out of time, so he decided to simply cross out some letters from the sentence. What smallest number of letters will he have to cross out? When a letter is crossed out, it is "removed" so that the letters to its left and right (if they existed), become neighboring. For example, if we cross out the first letter from the string "<span class=\"tex-font-style-tt\">aba</span>", we get the string "<span class=\"tex-font-style-tt\">ba</span>", and if we cross out the second letter, we get "<span class=\"tex-font-style-tt\">aa</span>".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters — that's the initial sentence in <span class=\"tex-span\"><i>N</i></span>-ish, written by Sergey. The length of string <span class=\"tex-span\"><i>s</i></span> doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\">5</sup></span>.</p><p>The next line contains integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ 13</span>) — the number of forbidden pairs of letters.</p><p>Next <span class=\"tex-span\"><i>k</i></span> lines contain descriptions of forbidden pairs of letters. Each line contains exactly two different lowercase Latin letters without separators that represent the forbidden pairs. It is guaranteed that each letter is included in no more than one pair.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the smallest number of letters that need to be removed to get a string without any forbidden pairs of neighboring letters. Please note that the answer always exists as it is always possible to remove all letters.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>ababa<br />1<br />ab<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>codeforces<br />2<br />do<br />cs<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you should remove two letters <span class=\"tex-font-style-tt\">b</span>.</p><p>In the second sample you should remove the second or the third letter. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Colliders"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Colliders</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>By 2312 there were <span class=\"tex-span\"><i>n</i></span> Large Hadron Colliders in the inhabited part of the universe. Each of them corresponded to a single natural number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. However, scientists did not know what activating several colliders simultaneously could cause, so the colliders were deactivated.</p><p>In 2312 there was a startling discovery: a collider's activity is safe if and only if all numbers of activated colliders are pairwise relatively prime to each other (two numbers are relatively prime if their greatest common divisor equals <span class=\"tex-span\">1</span>)! If two colliders with relatively nonprime numbers are activated, it will cause a global collapse.</p><p>Upon learning this, physicists rushed to turn the colliders on and off and carry out all sorts of experiments. To make sure than the scientists' quickness doesn't end with big trouble, the Large Hadron Colliders' Large Remote Control was created. You are commissioned to write the software for the remote (well, you do not expect anybody to operate it manually, do you?).</p><p>Initially, all colliders are deactivated. Your program receives multiple requests of the form \"activate/deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider\". The program should handle requests in the order of receiving them. The program should print the processed results in the format described below.</p><p>To the request of \"<span class=\"tex-font-style-tt\">+ i</span>\" (that is, to activate the <span class=\"tex-span\"><i>i</i></span>-th collider), the program should print exactly one of the following responses: </p><ul> <li> \"<span class=\"tex-font-style-tt\">Success</span>\" if the activation was successful. </li><li> \"<span class=\"tex-font-style-tt\">Already on</span>\", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already activated before the request. </li><li> \"<span class=\"tex-font-style-tt\">Conflict with j</span>\", if there is a conflict with the <span class=\"tex-span\"><i>j</i></span>-th collider (that is, the <span class=\"tex-span\"><i>j</i></span>-th collider is on, and numbers <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are not relatively prime). In this case, the <span class=\"tex-span\"><i>i</i></span>-th collider shouldn't be activated. If a conflict occurs with several colliders simultaneously, you should print the number of any of them. </li></ul><p>The request of \"<span class=\"tex-font-style-tt\">- i</span>\" (that is, to deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider), should receive one of the following responses from the program: </p><ul> <li> \"<span class=\"tex-font-style-tt\">Success</span>\", if the deactivation was successful. </li><li> \"<span class=\"tex-font-style-tt\">Already off</span>\", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already deactivated before the request. </li></ul><p>You don't need to print quotes in the output of the responses to the requests.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of colliders and the number of requests, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contain numbers of requests, one per line, in the form of either \"<span class=\"tex-font-style-tt\">+ i</span>\" (without the quotes) — activate the <span class=\"tex-span\"><i>i</i></span>-th collider, or \"<span class=\"tex-font-style-tt\">- i</span>\" (without the quotes) — deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>m</i></span> lines — the results of executing requests in the above given format. The requests should be processed in the order, in which they are given in the input. Don't forget that the responses to the requests should be printed without quotes.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br/>+ 6<br/>+ 10<br/>+ 5<br/>- 10<br/>- 5<br/>- 6<br/>+ 10<br/>+ 3<br/>+ 6<br/>+ 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Success<br/>Conflict with 6<br/>Success<br/>Already off<br/>Success<br/>Success<br/>Success<br/>Success<br/>Conflict with 10<br/>Already on<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Note that in the sample the colliders don't turn on after the second and ninth requests. The ninth request could also receive response \"<span class=\"tex-font-style-tt\">Conflict with 3</span>\".</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"cde2d6d19f8db50a27d431d979b3b9d7\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"8a1152c1a3447c2a9598d39de12f8b90b8cba4b6\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_ae568af950627ce284845616fc0a6712b5d0a58e\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Colliders</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>By 2312 there were <span class=\"tex-span\"><i>n</i></span> Large Hadron Colliders in the inhabited part of the universe. Each of them corresponded to a single natural number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. However, scientists did not know what activating several colliders simultaneously could cause, so the colliders were deactivated.</p><p>In 2312 there was a startling discovery: a collider's activity is safe if and only if all numbers of activated colliders are pairwise relatively prime to each other (two numbers are relatively prime if their greatest common divisor equals <span class=\"tex-span\">1</span>)! If two colliders with relatively nonprime numbers are activated, it will cause a global collapse.</p><p>Upon learning this, physicists rushed to turn the colliders on and off and carry out all sorts of experiments. To make sure than the scientists' quickness doesn't end with big trouble, the Large Hadron Colliders' Large Remote Control was created. You are commissioned to write the software for the remote (well, you do not expect anybody to operate it manually, do you?).</p><p>Initially, all colliders are deactivated. Your program receives multiple requests of the form "activate/deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider". The program should handle requests in the order of receiving them. The program should print the processed results in the format described below.</p><p>To the request of "<span class=\"tex-font-style-tt\">+ i</span>" (that is, to activate the <span class=\"tex-span\"><i>i</i></span>-th collider), the program should print exactly one of the following responses: </p><ul> <li> "<span class=\"tex-font-style-tt\">Success</span>" if the activation was successful. </li><li> "<span class=\"tex-font-style-tt\">Already on</span>", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already activated before the request. </li><li> "<span class=\"tex-font-style-tt\">Conflict with j</span>", if there is a conflict with the <span class=\"tex-span\"><i>j</i></span>-th collider (that is, the <span class=\"tex-span\"><i>j</i></span>-th collider is on, and numbers <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are not relatively prime). In this case, the <span class=\"tex-span\"><i>i</i></span>-th collider shouldn't be activated. If a conflict occurs with several colliders simultaneously, you should print the number of any of them. </li></ul><p>The request of "<span class=\"tex-font-style-tt\">- i</span>" (that is, to deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider), should receive one of the following responses from the program: </p><ul> <li> "<span class=\"tex-font-style-tt\">Success</span>", if the deactivation was successful. </li><li> "<span class=\"tex-font-style-tt\">Already off</span>", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already deactivated before the request. </li></ul><p>You don't need to print quotes in the output of the responses to the requests.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of colliders and the number of requests, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contain numbers of requests, one per line, in the form of either "<span class=\"tex-font-style-tt\">+ i</span>" (without the quotes) — activate the <span class=\"tex-span\"><i>i</i></span>-th collider, or "<span class=\"tex-font-style-tt\">- i</span>" (without the quotes) — deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>m</i></span> lines — the results of executing requests in the above given format. The requests should be processed in the order, in which they are given in the input. Don't forget that the responses to the requests should be printed without quotes.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br />+ 6<br />+ 10<br />+ 5<br />- 10<br />- 5<br />- 6<br />+ 10<br />+ 3<br />+ 6<br />+ 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Success<br />Conflict with 6<br />Success<br />Already off<br />Success<br />Success<br />Success<br />Success<br />Conflict with 10<br />Already on<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Note that in the sample the colliders don't turn on after the second and ninth requests. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-572107 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-572107\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3993\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input style=\"margin-left:1em\" type=\"radio\" name=\"locale\" value=\"ru\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In Russian</span>\r\n </div>\r\n <textarea 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Double Profiles"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Double Profiles</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You have been offered a job in a company developing a large social network. Your first task is connected with searching profiles that most probably belong to the same user.</p><p>The social network contains <span class=\"tex-span\"><i>n</i></span> registered profiles, numbered from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. Some pairs there are friends (the \"friendship\" relationship is mutual, that is, if <span class=\"tex-span\"><i>i</i></span> is friends with <span class=\"tex-span\"><i>j</i></span>, then <span class=\"tex-span\"><i>j</i></span> is also friends with <span class=\"tex-span\"><i>i</i></span>). Let's say that profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> (<span class=\"tex-span\"><i>i</i> ≠ <i>j</i></span>) are <span class=\"tex-font-style-it\">doubles</span>, if for any profile <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\"><i>k</i> ≠ <i>i</i></span>, <span class=\"tex-span\"><i>k</i> ≠ <i>j</i></span>) one of the two statements is true: either <span class=\"tex-span\"><i>k</i></span> is friends with <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span>, or <span class=\"tex-span\"><i>k</i></span> isn't friends with either of them. Also, <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> can be friends or not be friends.</p><p>Your task is to count the number of different unordered pairs (<span class=\"tex-span\"><i>i</i>, <i>j</i></span>), such that the profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are doubles. Note that the pairs are unordered, that is, pairs (<span class=\"tex-span\"><i>a</i>, <i>b</i></span>) and (<span class=\"tex-span\"><i>b</i>, <i>a</i></span>) are considered identical.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">6</sup></span>, <span class=\"tex-span\">0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">6</sup></span>), — the number of profiles and the number of pairs of friends, correspondingly. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contains descriptions of pairs of friends in the format \"<span class=\"tex-span\"><i>v</i> <i>u</i></span>\", where <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> (<span class=\"tex-span\">1 ≤ <i>v</i>, <i>u</i> ≤ <i>n</i>, <i>v</i> ≠ <i>u</i></span>) are numbers of profiles that are friends with each other. It is guaranteed that each unordered pair of friends occurs no more than once and no profile is friends with itself.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single integer — the number of unordered pairs of profiles that are doubles. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br/>1 2<br/>2 3<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first and second sample any two profiles are doubles.</p><p>In the third sample the doubles are pairs of profiles <span class=\"tex-span\">(1, 3)</span> and <span class=\"tex-span\">(2, 4)</span>.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"84e11e8ea5221aaf38277715496d16c0\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"8a1152c1a3447c2a9598d39de12f8b90b8cba4b6\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_cefe447eb5a76dadc3acb61e05626fb0ddba9cc5\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Double Profiles</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You have been offered a job in a company developing a large social network. Your first task is connected with searching profiles that most probably belong to the same user.</p><p>The social network contains <span class=\"tex-span\"><i>n</i></span> registered profiles, numbered from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. Some pairs there are friends (the "friendship" relationship is mutual, that is, if <span class=\"tex-span\"><i>i</i></span> is friends with <span class=\"tex-span\"><i>j</i></span>, then <span class=\"tex-span\"><i>j</i></span> is also friends with <span class=\"tex-span\"><i>i</i></span>). Let's say that profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> (<span class=\"tex-span\"><i>i</i> ≠ <i>j</i></span>) are <span class=\"tex-font-style-it\">doubles</span>, if for any profile <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\"><i>k</i> ≠ <i>i</i></span>, <span class=\"tex-span\"><i>k</i> ≠ <i>j</i></span>) one of the two statements is true: either <span class=\"tex-span\"><i>k</i></span> is friends with <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span>, or <span class=\"tex-span\"><i>k</i></span> isn't friends with either of them. Also, <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> can be friends or not be friends.</p><p>Your task is to count the number of different unordered pairs (<span class=\"tex-span\"><i>i</i>, <i>j</i></span>), such that the profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are doubles. Note that the pairs are unordered, that is, pairs (<span class=\"tex-span\"><i>a</i>, <i>b</i></span>) and (<span class=\"tex-span\"><i>b</i>, <i>a</i></span>) are considered identical.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">6</sup></span>, <span class=\"tex-span\">0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">6</sup></span>), — the number of profiles and the number of pairs of friends, correspondingly. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contains descriptions of pairs of friends in the format "<span class=\"tex-span\"><i>v</i> <i>u</i></span>", where <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> (<span class=\"tex-span\">1 ≤ <i>v</i>, <i>u</i> ≤ <i>n</i>, <i>v</i> ≠ <i>u</i></span>) are numbers of profiles that are friends with each other. It is guaranteed that each unordered pair of friends occurs no more than once and no profile is friends with itself.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single integer — the number of unordered pairs of profiles that are doubles. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br />1 2<br />2 3<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first and second sample any two profiles are doubles.</p><p>In the third sample the doubles are pairs of profiles <span class=\"tex-span\">(1, 3)</span> and <span class=\"tex-span\">(2, 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Flatland Fencing"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Flatland Fencing</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The King of Flatland will organize a knights' tournament! The winner will get half the kingdom and the favor of the princess of legendary beauty and wisdom. The final test of the applicants' courage and strength will be a fencing tournament. The tournament is held by the following rules: the participants fight one on one, the winner (or rather, the survivor) transfers to the next round.</p><p>Before the battle both participants stand at the specified points on the <span class=\"tex-span\"><i>Ox</i></span> axis with integer coordinates. Then they make moves in turn. The first participant moves first, naturally. During a move, the first participant can transfer from the point <span class=\"tex-span\"><i>x</i></span> to any integer point of the interval [<span class=\"tex-span\"><i>x</i> + <i>a</i></span>; <span class=\"tex-span\"><i>x</i> + <i>b</i></span>]. The second participant can transfer during a move to any integer point of the interval [<span class=\"tex-span\"><i>x</i> - <i>b</i></span>; <span class=\"tex-span\"><i>x</i> - <i>a</i></span>]. That is, the options for the players' moves are symmetric (note that the numbers <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> are not required to be positive, and if <span class=\"tex-span\"><i>a</i> ≤ 0 ≤ <i>b</i></span>, then staying in one place is a correct move). At any time the participants can be located arbitrarily relative to each other, that is, it is allowed to \"jump\" over the enemy in any direction. A participant wins if he uses his move to transfer to the point where his opponent is.</p><p>Of course, the princess has already chosen a husband and now she wants to make her sweetheart win the tournament. He has already reached the tournament finals and he is facing the last battle. The princess asks the tournament manager to arrange the tournament finalists in such a way that her sweetheart wins the tournament, considering that both players play optimally. However, the initial location of the participants has already been announced, and we can only pull some strings and determine which participant will be first and which one will be second. But how do we know which participant can secure the victory? Alas, the princess is not learned in the military affairs... Therefore, she asks you to determine how the battle will end considering that both opponents play optimally. Also, if the first player wins, your task is to determine his winning move.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains four space-separated integers — <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">2</sub></span>, <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> ≠ <i>x</i><sub class=\"lower-index\">2</sub></span>, <span class=\"tex-span\"><i>a</i> ≤ <i>b</i></span>, <span class=\"tex-span\"> - 10<sup class=\"upper-index\">9</sup> ≤ <i>x</i><sub class=\"lower-index\">1</sub>, <i>x</i><sub class=\"lower-index\">2</sub>, <i>a</i>, <i>b</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — coordinates of the points where the first and the second participant start, and the numbers that determine the players' moves, correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>On the first line print the outcome of the battle as \"<span class=\"tex-font-style-tt\">FIRST</span>\" (without the quotes), if both players play optimally and the first player wins. Print \"<span class=\"tex-font-style-tt\">SECOND</span>\" (without the quotes) if the second player wins and print \"<span class=\"tex-font-style-tt\">DRAW</span>\" (without the quotes), if nobody is able to secure the victory.</p><p>If the first player wins, print on the next line the single integer <span class=\"tex-span\"><i>x</i></span> — the coordinate of the point where the first player should transfer to win. The indicated move should be valid, that is, it should meet the following condition: <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> + <i>a</i> ≤ <i>x</i> ≤ <i>x</i><sub class=\"lower-index\">1</sub> + <i>b</i></span>. If there are several winning moves, print any of them. If the first participant can't secure the victory, then you do not have to print anything.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 0 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>FIRST<br/>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 1 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>SECOND<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 0 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>DRAW<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the first player can win in one move.</p><p>In the second sample the first participant must go to point <span class=\"tex-span\">1</span>, where the second participant immediately goes and wins. </p><p>In the third sample changing the position isn't profitable to either participant, so nobody wins.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"12a900102e00d5a478d67ae841d2c796\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"8a1152c1a3447c2a9598d39de12f8b90b8cba4b6\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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|| c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_117d5bb8e7192ca14ffad8247c3e202973b9366d\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Flatland Fencing</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The King of Flatland will organize a knights' tournament! The winner will get half the kingdom and the favor of the princess of legendary beauty and wisdom. The final test of the applicants' courage and strength will be a fencing tournament. The tournament is held by the following rules: the participants fight one on one, the winner (or rather, the survivor) transfers to the next round.</p><p>Before the battle both participants stand at the specified points on the <span class=\"tex-span\"><i>Ox</i></span> axis with integer coordinates. Then they make moves in turn. The first participant moves first, naturally. During a move, the first participant can transfer from the point <span class=\"tex-span\"><i>x</i></span> to any integer point of the interval [<span class=\"tex-span\"><i>x</i> + <i>a</i></span>; <span class=\"tex-span\"><i>x</i> + <i>b</i></span>]. The second participant can transfer during a move to any integer point of the interval [<span class=\"tex-span\"><i>x</i> - <i>b</i></span>; <span class=\"tex-span\"><i>x</i> - <i>a</i></span>]. That is, the options for the players' moves are symmetric (note that the numbers <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> are not required to be positive, and if <span class=\"tex-span\"><i>a</i> ≤ 0 ≤ <i>b</i></span>, then staying in one place is a correct move). At any time the participants can be located arbitrarily relative to each other, that is, it is allowed to "jump" over the enemy in any direction. A participant wins if he uses his move to transfer to the point where his opponent is.</p><p>Of course, the princess has already chosen a husband and now she wants to make her sweetheart win the tournament. He has already reached the tournament finals and he is facing the last battle. The princess asks the tournament manager to arrange the tournament finalists in such a way that her sweetheart wins the tournament, considering that both players play optimally. However, the initial location of the participants has already been announced, and we can only pull some strings and determine which participant will be first and which one will be second. But how do we know which participant can secure the victory? Alas, the princess is not learned in the military affairs... Therefore, she asks you to determine how the battle will end considering that both opponents play optimally. Also, if the first player wins, your task is to determine his winning move.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains four space-separated integers — <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub></span>, <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">2</sub></span>, <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> ≠ <i>x</i><sub class=\"lower-index\">2</sub></span>, <span class=\"tex-span\"><i>a</i> ≤ <i>b</i></span>, <span class=\"tex-span\"> - 10<sup class=\"upper-index\">9</sup> ≤ <i>x</i><sub class=\"lower-index\">1</sub>, <i>x</i><sub class=\"lower-index\">2</sub>, <i>a</i>, <i>b</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — coordinates of the points where the first and the second participant start, and the numbers that determine the players' moves, correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>On the first line print the outcome of the battle as "<span class=\"tex-font-style-tt\">FIRST</span>" (without the quotes), if both players play optimally and the first player wins. Print "<span class=\"tex-font-style-tt\">SECOND</span>" (without the quotes) if the second player wins and print "<span class=\"tex-font-style-tt\">DRAW</span>" (without the quotes), if nobody is able to secure the victory.</p><p>If the first player wins, print on the next line the single integer <span class=\"tex-span\"><i>x</i></span> — the coordinate of the point where the first player should transfer to win. The indicated move should be valid, that is, it should meet the following condition: <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\">1</sub> + <i>a</i> ≤ <i>x</i> ≤ <i>x</i><sub class=\"lower-index\">1</sub> + <i>b</i></span>. If there are several winning moves, print any of them. If the first participant can't secure the victory, then you do not have to print anything.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 0 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>FIRST<br />2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 1 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>SECOND<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>0 2 0 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>DRAW<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the first player can win in one move.</p><p>In the second sample the first participant must go to point <span class=\"tex-span\">1</span>, where the second participant immediately goes and wins. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Martian Colony"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Martian Colony</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>4 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The first ship with the Earth settlers landed on Mars. The colonists managed to build <span class=\"tex-span\"><i>n</i></span> necessary structures on the surface of the planet (which can be regarded as a plane, and the construction can be regarded as points on it). But one day the scanners recorded suspicious activity on the outskirts of the colony. It was decided to use the protective force field generating system to protect the colony against possible trouble.</p><p>The system works as follows: the surface contains a number of generators of the field (they can also be considered as points). The active range of each generator is a circle of radius <span class=\"tex-span\"><i>r</i></span> centered at the location of the generator (the boundary of the circle is also included in the range). After the system is activated, it stretches the protective force field <span class=\"tex-font-style-bf\">only over the part of the surface, which is within the area of all generators' activity</span>. That is, the protected part is the <span class=\"tex-font-style-bf\">intersection</span> of the generators' active ranges.</p><p>The number of generators available to the colonists is not limited, but the system of field generation consumes a lot of energy. More precisely, the energy consumption does not depend on the number of generators, but it is directly proportional to the <span class=\"tex-font-style-bf\">area</span>, which is protected by the field. Also, it is necessary that all the existing buildings are located within the protected area.</p><p>Determine the smallest possible area of the protected part of the surface containing all the buildings.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>r</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>, <span class=\"tex-span\">1 ≤ <i>r</i> ≤ 50000</span>) — the number of buildings and the active ranges of the generators, correspondingly.</p><p>Next <span class=\"tex-span\"><i>n</i></span> lines contains the buildings' coordinates. The <span class=\"tex-span\"><i>i</i> + 1</span>-th (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>) line contains two real numbers with at most three digits after the decimal point <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">|<i>x</i><sub class=\"lower-index\"><i>i</i></sub>|, |<i>y</i><sub class=\"lower-index\"><i>i</i></sub>| ≤ 50000</span>) — coordinates of the <span class=\"tex-span\"><i>i</i></span>-th building. It is guaranteed that no two buildings are located at the same point, and no two different buildings are located closer than <span class=\"tex-span\">1</span>.</p><p>It is guaranteed that there exists a circle with radius <span class=\"tex-span\"><i>r</i></span> that contains all the buildings.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the minimum area of the protected part containing all the buildings. The answer is accepted if absolute or relative error doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 4</sup></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 5<br/>0.00 0.000<br/>0.0 8.00<br/>6 8.00<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>78.5398163397<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1000<br/>0.0 0.0<br/>0 2.00<br/>2.00 2<br/>2.0 0.00<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4.0026666140<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br/>3.00 0.0<br/>-3 0.00<br/>0.000 1<br/>0.0 -1.00<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>8.1750554397<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the given radius equals the radius of the circle circumscribed around the given points. That's why the circle that corresponds to it is the sought area. The answer is <span class=\"tex-span\">25π</span>.</p><p>In the second sample the area nearly coincides with the square which has vertexes in the given points.</p><p>The area for the third sample is shown on the picture below.</p><center> <img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/bbf7435a0b532966f3e1edc36065e3e8e8b4b1e2.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/> </center></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"8dae5e7e8d755152ab2bbc12462f3be5\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"8a1152c1a3447c2a9598d39de12f8b90b8cba4b6\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Martian Colony</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>4 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The first ship with the Earth settlers landed on Mars. The colonists managed to build <span class=\"tex-span\"><i>n</i></span> necessary structures on the surface of the planet (which can be regarded as a plane, and the construction can be regarded as points on it). But one day the scanners recorded suspicious activity on the outskirts of the colony. It was decided to use the protective force field generating system to protect the colony against possible trouble.</p><p>The system works as follows: the surface contains a number of generators of the field (they can also be considered as points). The active range of each generator is a circle of radius <span class=\"tex-span\"><i>r</i></span> centered at the location of the generator (the boundary of the circle is also included in the range). After the system is activated, it stretches the protective force field <span class=\"tex-font-style-bf\">only over the part of the surface, which is within the area of all generators' activity</span>. That is, the protected part is the <span class=\"tex-font-style-bf\">intersection</span> of the generators' active ranges.</p><p>The number of generators available to the colonists is not limited, but the system of field generation consumes a lot of energy. More precisely, the energy consumption does not depend on the number of generators, but it is directly proportional to the <span class=\"tex-font-style-bf\">area</span>, which is protected by the field. Also, it is necessary that all the existing buildings are located within the protected area.</p><p>Determine the smallest possible area of the protected part of the surface containing all the buildings.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>r</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>, <span class=\"tex-span\">1 ≤ <i>r</i> ≤ 50000</span>) — the number of buildings and the active ranges of the generators, correspondingly.</p><p>Next <span class=\"tex-span\"><i>n</i></span> lines contains the buildings' coordinates. The <span class=\"tex-span\"><i>i</i> + 1</span>-th (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>) line contains two real numbers with at most three digits after the decimal point <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">|<i>x</i><sub class=\"lower-index\"><i>i</i></sub>|, |<i>y</i><sub class=\"lower-index\"><i>i</i></sub>| ≤ 50000</span>) — coordinates of the <span class=\"tex-span\"><i>i</i></span>-th building. It is guaranteed that no two buildings are located at the same point, and no two different buildings are located closer than <span class=\"tex-span\">1</span>.</p><p>It is guaranteed that there exists a circle with radius <span class=\"tex-span\"><i>r</i></span> that contains all the buildings.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — the minimum area of the protected part containing all the buildings. The answer is accepted if absolute or relative error doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 4</sup></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 5<br />0.00 0.000<br />0.0 8.00<br />6 8.00<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>78.5398163397<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1000<br />0.0 0.0<br />0 2.00<br />2.00 2<br />2.0 0.00<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4.0026666140<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 5<br />3.00 0.0<br />-3 0.00<br />0.000 1<br />0.0 -1.00<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>8.1750554397<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the given radius equals the radius of the circle circumscribed around the given points. That's why the circle that corresponds to it is the sought area. The answer is <span class=\"tex-span\">25π</span>.</p><p>In the second sample the area nearly coincides with the square which has vertexes in the given points.</p><p>The area for the third sample is shown on the picture below.</p><center> <img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/bbf7435a0b532966f3e1edc36065e3e8e8b4b1e2.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> </center></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=E]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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I_love_%username%"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. I_love_%username%</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya adores sport programming. He can't write programs but he loves to watch the contests' progress. Vasya even has a favorite coder and Vasya pays special attention to him.</p><p>One day Vasya decided to collect the results of all contests where his favorite coder participated and track the progress of his coolness. For each contest where this coder participated, he wrote out a single non-negative number — the number of points his favorite coder earned in the contest. Vasya wrote out the points for the contest in the order, in which the contests run (naturally, no two contests ran simultaneously).</p><p>Vasya considers a coder's performance in a contest <span class=\"tex-font-style-it\">amazing</span> in two situations: he can break either his best or his worst performance record. First, it is amazing if during the contest the coder earns strictly <span class=\"tex-font-style-bf\">more</span> points that he earned on each past contest. Second, it is amazing if during the contest the coder earns strictly <span class=\"tex-font-style-bf\">less</span> points that he earned on each past contest. A coder's first contest isn't considered amazing. Now he wants to count the number of amazing performances the coder had throughout his whole history of participating in contests. But the list of earned points turned out long and Vasya can't code... That's why he asks you to help him.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 1000</span>) — the number of contests where the coder participated.</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> space-separated non-negative integer numbers — they are the points which the coder has earned. The points are given in the chronological order. All points do not exceed <span class=\"tex-span\">10000</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of amazing performances the coder has had during his whole history of participating in the contests.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>5<br/>100 50 200 150 200<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10<br/>4664 6496 5814 7010 5762 5736 6944 4850 3698 7242<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the performances number 2 and 3 are amazing.</p><p>In the second sample the performances number 2, 4, 9 and 10 are amazing.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"d34a385766630decba0a8e9971a3dede\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"53cfcf027b0ac20ad3ac1145c1d27b2d8409d9a4\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/155\">Codeforces Round 109 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/155/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Brute force\">\r\n brute force\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *800\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='d34a385766630decba0a8e9971a3dede'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"949\"/>\r\n <input name=\"tagName\" type=\"hidden\" 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{\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3958\" title=\"Codeforces Round #109\" target=\"_blank\">Codeforces Round #109</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"371:372\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3969\" title=\"Codeforces Round #109: editorial\" target=\"_blank\">Tutorial</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"952:953\" resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/155\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/155/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/155/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/155/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/155/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/155/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/155/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/155/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n 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const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_5d3fe02cacfe7d2daaa33a2a74efd3598035114b\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. I_love_%username%</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya adores sport programming. He can't write programs but he loves to watch the contests' progress. Vasya even has a favorite coder and Vasya pays special attention to him.</p><p>One day Vasya decided to collect the results of all contests where his favorite coder participated and track the progress of his coolness. For each contest where this coder participated, he wrote out a single non-negative number — the number of points his favorite coder earned in the contest. Vasya wrote out the points for the contest in the order, in which the contests run (naturally, no two contests ran simultaneously).</p><p>Vasya considers a coder's performance in a contest <span class=\"tex-font-style-it\">amazing</span> in two situations: he can break either his best or his worst performance record. First, it is amazing if during the contest the coder earns strictly <span class=\"tex-font-style-bf\">more</span> points that he earned on each past contest. Second, it is amazing if during the contest the coder earns strictly <span class=\"tex-font-style-bf\">less</span> points that he earned on each past contest. A coder's first contest isn't considered amazing. Now he wants to count the number of amazing performances the coder had throughout his whole history of participating in contests. But the list of earned points turned out long and Vasya can't code... That's why he asks you to help him.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 1000</span>) — the number of contests where the coder participated.</p><p>The next line contains <span class=\"tex-span\"><i>n</i></span> space-separated non-negative integer numbers — they are the points which the coder has earned. The points are given in the chronological order. All points do not exceed <span class=\"tex-span\">10000</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of amazing performances the coder has had during his whole history of participating in the contests.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>5<br />100 50 200 150 200<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>10<br />4664 6496 5814 7010 5762 5736 6944 4850 3698 7242<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the performances number 2 and 3 are amazing.</p><p>In the second sample the performances number 2, 4, 9 and 10 are 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: 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dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" 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class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Combination"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Combination</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Ilya plays a card game by the following rules.</p><p>A player has several cards. Each card contains two non-negative integers inscribed, one at the top of the card and one at the bottom. At the beginning of the round the player chooses one of his cards to play it. If the top of the card contains number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and the bottom contains number <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, then when the player is playing the card, he gets <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> points and also gets the opportunity to play additional <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> cards. After the playing the card is discarded.</p><p>More formally: let's say that there is a counter of the cards that can be played. At the beginning of the round the counter equals one. When a card is played, the counter decreases by one for the played card and increases by the number <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, which is written at the bottom of the card. Then the played card is discarded. If after that the counter is not equal to zero, the player gets the opportunity to play another card from the remaining cards. The round ends when the counter reaches zero or the player runs out of cards.</p><p>Of course, Ilya wants to get as many points as possible. Can you determine the maximum number of points he can score provided that you know his cards?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 1000</span>) — the number of cards Ilya has.</p><p>Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains two non-negative space-separated integers — <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub>, <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the numbers, written at the top and the bottom of the <span class=\"tex-span\"><i>i</i></span>-th card correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the maximum number of points you can score in one round by the described rules.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>1 0<br/>2 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br/>1 0<br/>2 0<br/>0 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample none of two cards brings extra moves, so you should play the one that will bring more points.</p><p>In the second sample you should first play the third card that doesn't bring any points but lets you play both remaining cards.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"882aeb29f2fe37bfcb937502a1c4a27d\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"53cfcf027b0ac20ad3ac1145c1d27b2d8409d9a4\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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|| c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_6b583a913b7fb98fa0dde39946b67803a2adfb51\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Combination</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Ilya plays a card game by the following rules.</p><p>A player has several cards. Each card contains two non-negative integers inscribed, one at the top of the card and one at the bottom. At the beginning of the round the player chooses one of his cards to play it. If the top of the card contains number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and the bottom contains number <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, then when the player is playing the card, he gets <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> points and also gets the opportunity to play additional <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> cards. After the playing the card is discarded.</p><p>More formally: let's say that there is a counter of the cards that can be played. At the beginning of the round the counter equals one. When a card is played, the counter decreases by one for the played card and increases by the number <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, which is written at the bottom of the card. Then the played card is discarded. If after that the counter is not equal to zero, the player gets the opportunity to play another card from the remaining cards. The round ends when the counter reaches zero or the player runs out of cards.</p><p>Of course, Ilya wants to get as many points as possible. Can you determine the maximum number of points he can score provided that you know his cards?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 1000</span>) — the number of cards Ilya has.</p><p>Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains two non-negative space-separated integers — <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub>, <i>b</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the numbers, written at the top and the bottom of the <span class=\"tex-span\"><i>i</i></span>-th card correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the maximum number of points you can score in one round by the described rules.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />1 0<br />2 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br />1 0<br />2 0<br />0 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample none of two cards brings extra moves, so you should play the one that will bring more points.</p><p>In the second sample you should first play the third card that doesn't bring any points but lets you play both remaining cards.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Hometask"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Hometask</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sergey attends lessons of the <span class=\"tex-span\"><i>N</i></span>-ish language. Each lesson he receives a hometask. This time the task is to translate some sentence to the <span class=\"tex-span\"><i>N</i></span>-ish language. Sentences of the <span class=\"tex-span\"><i>N</i></span>-ish language can be represented as strings consisting of lowercase Latin letters without spaces or punctuation marks.</p><p>Sergey totally forgot about the task until half an hour before the next lesson and hastily scribbled something down. But then he recollected that in the last lesson he learned the grammar of <span class=\"tex-span\"><i>N</i></span>-ish. The spelling rules state that <span class=\"tex-span\"><i>N</i></span>-ish contains some \"forbidden\" pairs of letters: such letters can never occur in a sentence next to each other. Also, the order of the letters doesn't matter (for example, if the pair of letters \"<span class=\"tex-font-style-tt\">ab</span>\" is forbidden, then any occurrences of substrings \"<span class=\"tex-font-style-tt\">ab</span>\" and \"<span class=\"tex-font-style-tt\">ba</span>\" are also forbidden). Also, each pair has different letters and each letter occurs in no more than one forbidden pair.</p><p>Now Sergey wants to correct his sentence so that it doesn't contain any \"forbidden\" pairs of letters that stand next to each other. However, he is running out of time, so he decided to simply cross out some letters from the sentence. What smallest number of letters will he have to cross out? When a letter is crossed out, it is \"removed\" so that the letters to its left and right (if they existed), become neighboring. For example, if we cross out the first letter from the string \"<span class=\"tex-font-style-tt\">aba</span>\", we get the string \"<span class=\"tex-font-style-tt\">ba</span>\", and if we cross out the second letter, we get \"<span class=\"tex-font-style-tt\">aa</span>\".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters — that's the initial sentence in <span class=\"tex-span\"><i>N</i></span>-ish, written by Sergey. The length of string <span class=\"tex-span\"><i>s</i></span> doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\">5</sup></span>.</p><p>The next line contains integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ 13</span>) — the number of forbidden pairs of letters.</p><p>Next <span class=\"tex-span\"><i>k</i></span> lines contain descriptions of forbidden pairs of letters. Each line contains exactly two different lowercase Latin letters without separators that represent the forbidden pairs. It is guaranteed that each letter is included in no more than one pair.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the smallest number of letters that need to be removed to get a string without any forbidden pairs of neighboring letters. Please note that the answer always exists as it is always possible to remove all letters.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>ababa<br/>1<br/>ab<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>codeforces<br/>2<br/>do<br/>cs<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you should remove two letters <span class=\"tex-font-style-tt\">b</span>.</p><p>In the second sample you should remove the second or the third letter. 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resourceName=\"Tutorial\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/155\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/155/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/155/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/155/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/155/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/155/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/155/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/155/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox 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|| c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_80bfc89a1dde0206ffef458a633c434912ebabd6\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Hometask</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sergey attends lessons of the <span class=\"tex-span\"><i>N</i></span>-ish language. Each lesson he receives a hometask. This time the task is to translate some sentence to the <span class=\"tex-span\"><i>N</i></span>-ish language. Sentences of the <span class=\"tex-span\"><i>N</i></span>-ish language can be represented as strings consisting of lowercase Latin letters without spaces or punctuation marks.</p><p>Sergey totally forgot about the task until half an hour before the next lesson and hastily scribbled something down. But then he recollected that in the last lesson he learned the grammar of <span class=\"tex-span\"><i>N</i></span>-ish. The spelling rules state that <span class=\"tex-span\"><i>N</i></span>-ish contains some "forbidden" pairs of letters: such letters can never occur in a sentence next to each other. Also, the order of the letters doesn't matter (for example, if the pair of letters "<span class=\"tex-font-style-tt\">ab</span>" is forbidden, then any occurrences of substrings "<span class=\"tex-font-style-tt\">ab</span>" and "<span class=\"tex-font-style-tt\">ba</span>" are also forbidden). Also, each pair has different letters and each letter occurs in no more than one forbidden pair.</p><p>Now Sergey wants to correct his sentence so that it doesn't contain any "forbidden" pairs of letters that stand next to each other. However, he is running out of time, so he decided to simply cross out some letters from the sentence. What smallest number of letters will he have to cross out? When a letter is crossed out, it is "removed" so that the letters to its left and right (if they existed), become neighboring. For example, if we cross out the first letter from the string "<span class=\"tex-font-style-tt\">aba</span>", we get the string "<span class=\"tex-font-style-tt\">ba</span>", and if we cross out the second letter, we get "<span class=\"tex-font-style-tt\">aa</span>".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters — that's the initial sentence in <span class=\"tex-span\"><i>N</i></span>-ish, written by Sergey. The length of string <span class=\"tex-span\"><i>s</i></span> doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\">5</sup></span>.</p><p>The next line contains integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ 13</span>) — the number of forbidden pairs of letters.</p><p>Next <span class=\"tex-span\"><i>k</i></span> lines contain descriptions of forbidden pairs of letters. Each line contains exactly two different lowercase Latin letters without separators that represent the forbidden pairs. It is guaranteed that each letter is included in no more than one pair.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the smallest number of letters that need to be removed to get a string without any forbidden pairs of neighboring letters. Please note that the answer always exists as it is always possible to remove all letters.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>ababa<br />1<br />ab<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>codeforces<br />2<br />do<br />cs<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you should remove two letters <span class=\"tex-font-style-tt\">b</span>.</p><p>In the second sample you should remove the second or the third letter. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Colliders"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Colliders</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>By 2312 there were <span class=\"tex-span\"><i>n</i></span> Large Hadron Colliders in the inhabited part of the universe. Each of them corresponded to a single natural number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. However, scientists did not know what activating several colliders simultaneously could cause, so the colliders were deactivated.</p><p>In 2312 there was a startling discovery: a collider's activity is safe if and only if all numbers of activated colliders are pairwise relatively prime to each other (two numbers are relatively prime if their greatest common divisor equals <span class=\"tex-span\">1</span>)! If two colliders with relatively nonprime numbers are activated, it will cause a global collapse.</p><p>Upon learning this, physicists rushed to turn the colliders on and off and carry out all sorts of experiments. To make sure than the scientists' quickness doesn't end with big trouble, the Large Hadron Colliders' Large Remote Control was created. You are commissioned to write the software for the remote (well, you do not expect anybody to operate it manually, do you?).</p><p>Initially, all colliders are deactivated. Your program receives multiple requests of the form \"activate/deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider\". The program should handle requests in the order of receiving them. The program should print the processed results in the format described below.</p><p>To the request of \"<span class=\"tex-font-style-tt\">+ i</span>\" (that is, to activate the <span class=\"tex-span\"><i>i</i></span>-th collider), the program should print exactly one of the following responses: </p><ul> <li> \"<span class=\"tex-font-style-tt\">Success</span>\" if the activation was successful. </li><li> \"<span class=\"tex-font-style-tt\">Already on</span>\", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already activated before the request. </li><li> \"<span class=\"tex-font-style-tt\">Conflict with j</span>\", if there is a conflict with the <span class=\"tex-span\"><i>j</i></span>-th collider (that is, the <span class=\"tex-span\"><i>j</i></span>-th collider is on, and numbers <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are not relatively prime). In this case, the <span class=\"tex-span\"><i>i</i></span>-th collider shouldn't be activated. If a conflict occurs with several colliders simultaneously, you should print the number of any of them. </li></ul><p>The request of \"<span class=\"tex-font-style-tt\">- i</span>\" (that is, to deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider), should receive one of the following responses from the program: </p><ul> <li> \"<span class=\"tex-font-style-tt\">Success</span>\", if the deactivation was successful. </li><li> \"<span class=\"tex-font-style-tt\">Already off</span>\", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already deactivated before the request. </li></ul><p>You don't need to print quotes in the output of the responses to the requests.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of colliders and the number of requests, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contain numbers of requests, one per line, in the form of either \"<span class=\"tex-font-style-tt\">+ i</span>\" (without the quotes) — activate the <span class=\"tex-span\"><i>i</i></span>-th collider, or \"<span class=\"tex-font-style-tt\">- i</span>\" (without the quotes) — deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>m</i></span> lines — the results of executing requests in the above given format. The requests should be processed in the order, in which they are given in the input. Don't forget that the responses to the requests should be printed without quotes.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br/>+ 6<br/>+ 10<br/>+ 5<br/>- 10<br/>- 5<br/>- 6<br/>+ 10<br/>+ 3<br/>+ 6<br/>+ 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Success<br/>Conflict with 6<br/>Success<br/>Already off<br/>Success<br/>Success<br/>Success<br/>Success<br/>Conflict with 10<br/>Already on<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Note that in the sample the colliders don't turn on after the second and ninth requests. The ninth request could also receive response \"<span class=\"tex-font-style-tt\">Conflict with 3</span>\".</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"c3478188f45f5d4bc3f030ee373459f3\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"53cfcf027b0ac20ad3ac1145c1d27b2d8409d9a4\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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data-uuid=\"ps_5a909874e1060303e6bb88841cceadf00e178154\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Colliders</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>By 2312 there were <span class=\"tex-span\"><i>n</i></span> Large Hadron Colliders in the inhabited part of the universe. Each of them corresponded to a single natural number from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. However, scientists did not know what activating several colliders simultaneously could cause, so the colliders were deactivated.</p><p>In 2312 there was a startling discovery: a collider's activity is safe if and only if all numbers of activated colliders are pairwise relatively prime to each other (two numbers are relatively prime if their greatest common divisor equals <span class=\"tex-span\">1</span>)! If two colliders with relatively nonprime numbers are activated, it will cause a global collapse.</p><p>Upon learning this, physicists rushed to turn the colliders on and off and carry out all sorts of experiments. To make sure than the scientists' quickness doesn't end with big trouble, the Large Hadron Colliders' Large Remote Control was created. You are commissioned to write the software for the remote (well, you do not expect anybody to operate it manually, do you?).</p><p>Initially, all colliders are deactivated. Your program receives multiple requests of the form "activate/deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider". The program should handle requests in the order of receiving them. The program should print the processed results in the format described below.</p><p>To the request of "<span class=\"tex-font-style-tt\">+ i</span>" (that is, to activate the <span class=\"tex-span\"><i>i</i></span>-th collider), the program should print exactly one of the following responses: </p><ul> <li> "<span class=\"tex-font-style-tt\">Success</span>" if the activation was successful. </li><li> "<span class=\"tex-font-style-tt\">Already on</span>", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already activated before the request. </li><li> "<span class=\"tex-font-style-tt\">Conflict with j</span>", if there is a conflict with the <span class=\"tex-span\"><i>j</i></span>-th collider (that is, the <span class=\"tex-span\"><i>j</i></span>-th collider is on, and numbers <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are not relatively prime). In this case, the <span class=\"tex-span\"><i>i</i></span>-th collider shouldn't be activated. If a conflict occurs with several colliders simultaneously, you should print the number of any of them. </li></ul><p>The request of "<span class=\"tex-font-style-tt\">- i</span>" (that is, to deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider), should receive one of the following responses from the program: </p><ul> <li> "<span class=\"tex-font-style-tt\">Success</span>", if the deactivation was successful. </li><li> "<span class=\"tex-font-style-tt\">Already off</span>", if the <span class=\"tex-span\"><i>i</i></span>-th collider was already deactivated before the request. </li></ul><p>You don't need to print quotes in the output of the responses to the requests.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of colliders and the number of requests, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contain numbers of requests, one per line, in the form of either "<span class=\"tex-font-style-tt\">+ i</span>" (without the quotes) — activate the <span class=\"tex-span\"><i>i</i></span>-th collider, or "<span class=\"tex-font-style-tt\">- i</span>" (without the quotes) — deactivate the <span class=\"tex-span\"><i>i</i></span>-th collider (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>m</i></span> lines — the results of executing requests in the above given format. The requests should be processed in the order, in which they are given in the input. Don't forget that the responses to the requests should be printed without quotes.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>10 10<br />+ 6<br />+ 10<br />+ 5<br />- 10<br />- 5<br />- 6<br />+ 10<br />+ 3<br />+ 6<br />+ 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Success<br />Conflict with 6<br />Success<br />Already off<br />Success<br />Success<br />Success<br />Success<br />Conflict with 10<br />Already on<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Note that in the sample the colliders don't turn on after the second and ninth requests. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-572107 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-572107\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-3993\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input style=\"margin-left:1em\" type=\"radio\" name=\"locale\" value=\"ru\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In Russian</span>\r\n </div>\r\n <textarea 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Double Profiles"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Double Profiles</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You have been offered a job in a company developing a large social network. Your first task is connected with searching profiles that most probably belong to the same user.</p><p>The social network contains <span class=\"tex-span\"><i>n</i></span> registered profiles, numbered from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. Some pairs there are friends (the \"friendship\" relationship is mutual, that is, if <span class=\"tex-span\"><i>i</i></span> is friends with <span class=\"tex-span\"><i>j</i></span>, then <span class=\"tex-span\"><i>j</i></span> is also friends with <span class=\"tex-span\"><i>i</i></span>). Let's say that profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> (<span class=\"tex-span\"><i>i</i> ≠ <i>j</i></span>) are <span class=\"tex-font-style-it\">doubles</span>, if for any profile <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\"><i>k</i> ≠ <i>i</i></span>, <span class=\"tex-span\"><i>k</i> ≠ <i>j</i></span>) one of the two statements is true: either <span class=\"tex-span\"><i>k</i></span> is friends with <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span>, or <span class=\"tex-span\"><i>k</i></span> isn't friends with either of them. Also, <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> can be friends or not be friends.</p><p>Your task is to count the number of different unordered pairs (<span class=\"tex-span\"><i>i</i>, <i>j</i></span>), such that the profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are doubles. Note that the pairs are unordered, that is, pairs (<span class=\"tex-span\"><i>a</i>, <i>b</i></span>) and (<span class=\"tex-span\"><i>b</i>, <i>a</i></span>) are considered identical.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">6</sup></span>, <span class=\"tex-span\">0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">6</sup></span>), — the number of profiles and the number of pairs of friends, correspondingly. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contains descriptions of pairs of friends in the format \"<span class=\"tex-span\"><i>v</i> <i>u</i></span>\", where <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> (<span class=\"tex-span\">1 ≤ <i>v</i>, <i>u</i> ≤ <i>n</i>, <i>v</i> ≠ <i>u</i></span>) are numbers of profiles that are friends with each other. It is guaranteed that each unordered pair of friends occurs no more than once and no profile is friends with itself.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single integer — the number of unordered pairs of profiles that are doubles. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br/>1 2<br/>2 3<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br/>1 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first and second sample any two profiles are doubles.</p><p>In the third sample the doubles are pairs of profiles <span class=\"tex-span\">(1, 3)</span> and <span class=\"tex-span\">(2, 4)</span>.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"088691c37ad5cb7e91ff94bb5f055516\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"53cfcf027b0ac20ad3ac1145c1d27b2d8409d9a4\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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|| c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"E\" data-uuid=\"ps_400c081dfb07b61249fb8bd203bfac3e85221f87\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Double Profiles</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You have been offered a job in a company developing a large social network. Your first task is connected with searching profiles that most probably belong to the same user.</p><p>The social network contains <span class=\"tex-span\"><i>n</i></span> registered profiles, numbered from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. Some pairs there are friends (the "friendship" relationship is mutual, that is, if <span class=\"tex-span\"><i>i</i></span> is friends with <span class=\"tex-span\"><i>j</i></span>, then <span class=\"tex-span\"><i>j</i></span> is also friends with <span class=\"tex-span\"><i>i</i></span>). Let's say that profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> (<span class=\"tex-span\"><i>i</i> ≠ <i>j</i></span>) are <span class=\"tex-font-style-it\">doubles</span>, if for any profile <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\"><i>k</i> ≠ <i>i</i></span>, <span class=\"tex-span\"><i>k</i> ≠ <i>j</i></span>) one of the two statements is true: either <span class=\"tex-span\"><i>k</i></span> is friends with <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span>, or <span class=\"tex-span\"><i>k</i></span> isn't friends with either of them. Also, <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> can be friends or not be friends.</p><p>Your task is to count the number of different unordered pairs (<span class=\"tex-span\"><i>i</i>, <i>j</i></span>), such that the profiles <span class=\"tex-span\"><i>i</i></span> and <span class=\"tex-span\"><i>j</i></span> are doubles. Note that the pairs are unordered, that is, pairs (<span class=\"tex-span\"><i>a</i>, <i>b</i></span>) and (<span class=\"tex-span\"><i>b</i>, <i>a</i></span>) are considered identical.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">6</sup></span>, <span class=\"tex-span\">0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">6</sup></span>), — the number of profiles and the number of pairs of friends, correspondingly. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines contains descriptions of pairs of friends in the format "<span class=\"tex-span\"><i>v</i> <i>u</i></span>", where <span class=\"tex-span\"><i>v</i></span> and <span class=\"tex-span\"><i>u</i></span> (<span class=\"tex-span\">1 ≤ <i>v</i>, <i>u</i> ≤ <i>n</i>, <i>v</i> ≠ <i>u</i></span>) are numbers of profiles that are friends with each other. It is guaranteed that each unordered pair of friends occurs no more than once and no profile is friends with itself.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single integer — the number of unordered pairs of profiles that are doubles. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 3<br />1 2<br />2 3<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br />1 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first and second sample any two profiles are doubles.</p><p>In the third sample the doubles are pairs of profiles <span class=\"tex-span\">(1, 3)</span> and <span class=\"tex-span\">(2, 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:17</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='f99f4b663b9a9b4b054f93fb1554ee98'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/Endagorion\">Endagorion</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/Endagorion\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/Endagorion\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/Endagorion\">Submissions</a></li>\r\n <li><a\r\n href=\"/groups/with/Endagorion\">Groups</a></li>\r\n <li><a\r\n href=\"/contests/with/Endagorion\">Contests</a></li>\r\n <li><a\r\n href=\"/contests/writer/Endagorion\">Problemsetting</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/Endagorion\" style=\"text-decoration:none;color:black !important;\">Endagorion's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"3983\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/3969\"> <p>Codeforces Round #109: editorial</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/Endagorion\" title=\"International Grandmaster Endagorion\" class=\"rated-user user-red\">Endagorion</a>,\r\n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>,\r\n translation,\r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p><a href=\"/contest/155/problem/A\" title=\"Codeforces Round 109 (Div. 2)\">155A - I_love_\\%username\\%</a></p><p>You should do what is written: go through the sequence and count the elements which are greater or less than all of its predecessors. We don't even have to store the whole sequence, just the current minimum and maximum. Complexity — O(N), but squared still works fine.</p><p><a href=\"/contest/155/problem/B\" title=\"Codeforces Round 109 (Div. 2)\">155B - Combination</a></p><p>Clearly, we can play the cards with <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> > 0 first as each of them gives at least one extra move. After that, the number of extra moves left doesn't depend on the order of playing. The left cards all have <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span> = 0, so we play those of them which have larger <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>. Simpler version of this solution: sort all the cards by decrease of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>, if equal — by decrease of <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, and then go through the sorted array from beginning to end, simulate the counter and sum up the points. Remember not to fall over the edge of array if the sum of <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>i</i></sub></span>'s is larger than the number of cards. Complexity — O(n log n) (or O(n^2), if using bubblesort, which is still accepted).</p><p><a href=\"/contest/155/problem/C\" title=\"Codeforces Round 109 (Div. 2)\">155C - Hometask</a></p><p><a href=\"/contest/154/problem/A\" title=\"Codeforces Round 109 (Div. 1)\">154A - Hometask</a></p><p>Constriction saying that no letter occurs in more than one forbidden pair lets us to use the greedy solution. Without the constriction the problem is quite hard.</p><p>Let's look at all occurences of letters from some pair. They form several continuous substrings divided by some other letters. We can note that in optimal solution the substrings cannot merge, 'cause we can leave at least one letter in each of such parts. So, for each of these substrings problem is solved independently. To resolve conflicts within a substring, one has to remove all letters of some kind, 'cause while there are letters of both kinds there will be conflicts. Clearly, from each continuous substring of forbidden letters we remove all letters of the kind which number is less than another.</p><p>The answer can be counted in O(kN) with k runs through the string.</p><p><a href=\"/contest/155/problem/D\" title=\"Codeforces Round 109 (Div. 2)\">155D - Colliders</a></p><p><a href=\"/contest/154/problem/B\" title=\"Codeforces Round 109 (Div. 1)\">154B - Colliders</a></p><p>The clueless solution ''store all the enabled numbers and compare each new number with each of them'' works too slow, as we can add all the prime numbers below <span class=\"tex-span\"><i>n</i></span>, number of which is O(n / log n).</p><p>We can note that for each number k > 1 at any time no more than one collider is turned on which number is divided by k. Let us store an array which has in k-th element the number of turned-on collider which is divided by k, on 0 if there is no such at the moment. To enable the collider with number q we can look over q's divisors and check whether all the array's elements with these numbers have 0's. If some of them has a positive integer, that's the number of collider we conflict with — we can just print it and go on. Otherwise, we have to put q into all the overlooked elements.</p><p>This works in O(M sqrt(N) + N). There's faster solution as we can store all of the above only for prime divisors. Total size of the prime divisors list for number from 1 to N is O(N log log N). Thus we have a solution with complexity O(N log log N + M log N), as the number of prime divisors of k doesn't exceed log k (exact upper bound — log k / log log k * (1 + o(1)).</p><p><a href=\"/contest/155/problem/E\" title=\"Codeforces Round 109 (Div. 2)\">155E - Double Profiles</a></p><p><a href=\"/contest/154/problem/C\" title=\"Codeforces Round 109 (Div. 1)\">154C - Double Profiles</a></p><p>We want to count the number of pairs of vertices in a undirected graph which neighbours' sets are equal up to these vertices. To count the pairs which sets of neighbours are equal we can hash these sets (for instance, count the polynomial hash of adjacency matrix row) and sort the hashes. Than we have to add the pairs of doubles which have an edge between them.</p><p>We can note that there are no more such pairs than there are edges in the graph. So we can iterate through edges and check hashes for equivalence considering the presence of the edge (in case of polynomial hash we just add some degrees to them and then compare them). Other solution was to count another version of the previous hash, now adding a loop to each vertex, and to count the number of pairs just like in the previous case.</p><p>Moreover, we could try and sort the whole lists of adjacencies (which previuosly should be sorted too). As their total size is 2M, this works fine too, but needs an accurate realization. Hash solution complexity — O(N log N + M).</p><p><a href=\"/contest/154/problem/D\" title=\"Codeforces Round 109 (Div. 1)\">154D - Flatland Fencing</a></p><p>As the moves choices are symmetrical for both players, if one player can reach another in one move from some disposition, the other player also can reach the first. So, if we are allowed to stand in one place (i.e. a <= 0 <= b), we can just stand still and wait for another player to come. If she wants to win, she will have to step within our reach before that so that we can get her. So, if the first player doesn't reach the second initially, there is a draw as no one can ensure her victory. Thus we finished the case a <= 0 <= b: either the first player wins in one move, or there is a draw.</p><p>Now, let a and b have the same sign. Denote d = x2 — x1. If a <= b < 0, we can go to the situation with (d, a, b) = (-d, -b, -a), which is similar to the initial. So later on 0 < a.</p><p>So we have the following game: there are integers d and 0 < a <= b. In one move each player can substract an arbitrary integer number from segment [a; b] from d. The player who gets d = 0 after her move wins. If at some point d < 0, a draw is proclaimed (as no one can win anymore).</p><p>The interesting case is d > 0. Note that if d mod (a + b) = 0, the second player can use the symmetrical strategy: for every first player's move x of she can make a move a + b — x, and support the condition d mod (a + b) = 0. As d decreases, the second player eventually moves to 0 and wins. So, if d mod (a + b) = 0, the second player wins. Thus, if d mod (a + b) is in [a; b], the first player wins, as he can reduce the game to the previous case by letting the second player move in the losing situation.</p><p>What about all the other situations? Turns out all the other position are draws. We prove that by induction: let d = k(a + b) + l, where l in [0; a + b). Case l = 0, as we just proved, is losing, cases l in [a; b] are winning. If l is in [1; a — 1], we cannot move to losing position (we use the induction assumption for lesser k), but after the move a, we move to the draw position (if k = 0, we move to the negative number, otherwise we get into [(k — 1)(a + b) + b + 1; k(a + b) — 1] segment, every position from which is a draw by assumption). Similarily for l = [b + 1; a + b — 1], move to a draw — b.</p><p><a href=\"/contest/154/problem/E\" title=\"Codeforces Round 109 (Div. 1)\">154E - Martian Colony</a></p><p>We have to find the area of intersection of all circles containing the given set of points (it's clear that the intersection has the least area, and we have an unlimited number of circles). First, what shape does such an intersection have? Its border contains some circle arcs of radius R meeting at some points of convex hull. If we determine which points are present in the border, we can count the total area as the sum of polygon area and several circle segments.</p><p>So, how to determine those points? It's clear that if there is a circle of radius R containing all the points and having some of them on its border, then this particular point is present in the border of the intersection. If we fix the circle and move it in some direction, it eventually will run into some point — so we can find at least one point. Then we can perform something similar to ''present wrapping'' — go around the convex hull and support the set of the border points while controlling the relative position of the arcs. While this solution is fast, it is very hard to write and it was not assumed that it should be written during the contest.</p><p>There is much simpler solution based on quite different idea. We build the convex hull of the set so that no three points lie on the same line. Let us take the very large R so that every point of convex hull is present in the intersection border. As we gradually decrease R, some points will start to disappear from the border. How to determine which point falls out first? For point u in the convex hull denote its left and right neighbours l(u) and r(u). It's clear, that the first point to disappear will be such point u which has the largest radius of circle going through u, l(u) and r(u) (when R becomes equal to this radius, two arcs will merge into one in point u, while all the other will have joints in them; we will call this radius critical for u). Then we remove u from convex hull and do not take it into account. We repeat while the largest critical radius is larger than R. The rest points will be exactly the points forming the border.</p><p>How to do this fast? Note that when we remove some point from the set the critical radii will change only for its two neighbours. Let us store a priority queue containing critical radii along with point numbers. On every iteration we extract the largest critical radius, remove the corresponding point from the set, and refresh the information about the neighbours in the queue. We repeat while the largest radius is greater than R. As we just simulate the process of R decreasing, everything works correctly. The complexity of this procedure is O(n log n), as we have no more than n iterations and on every iteration we perform the constant number of operations with the queue of size at most n.</p><p>There is an unclear case, when the border contains only two points. Then on the last phase we have three points in the set and the algorithm doesn't have a clue which one to remove as they have equal critical radii. But we know that the triangle with vertices in these points is obtuse-angled, as we cannot shrink the circumcircle of an acute-angle triangle, as that would contradict with the circle existence condition. So we have to remove the point with the obtuse angle.</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/154\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 1)</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/155\" class=\"notice\" style=\"text-decoration: none;\">Codeforces Round 109 (Div. 2)</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-989-3983\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"989\",\n blogEntryId: \"3969\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+43</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-3983\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Endagorion\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Endagorion\">\n Endagorion\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Feb/25/2012 17:31\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/3969#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/3969#comments\">\n 16\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"3993\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (11)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80279\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Matjaz\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Matjaz\" title=\"Expert Matjaz\" class=\"rated-user user-blue\">Matjaz</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/26/2012 06:46\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80279\" href=\"?#comment-80279\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80279\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"4171\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80279\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Is there also an English version?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80279 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80279 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80279\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80375\" commentParentId=\"80279\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/cholerikasi\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44515/avatar/782a6a535da57281.jpg'/> </a>\n <div><a href=\"/profile/cholerikasi\" title=\"Specialist cholerikasi\" class=\"rated-user user-cyan\">cholerikasi</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 03:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80375\" href=\"?#comment-80375\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80279\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80375\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44515\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80375\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Translation is available when you click on the British flag in the top right of the page. I don't know why it switches to the Russian version when you come from the main page.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80375 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80375 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80375\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"80382\" commentParentId=\"80375\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/adito\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/44343/avatar/837907cd06499809.jpg'/> </a>\n <div><a href=\"/profile/adito\" title=\"Specialist adito\" class=\"rated-user user-cyan\">adito</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/27/2012 12:45\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-80382\" href=\"?#comment-80382\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-80375\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"80382\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"5\"\r\n data-commentUserId=\"44343\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+5</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-80382\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I think it's because the link in the previous page is <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.ru</a>. If you want to see the english version, go to <a href=\"https://codeforces.com/blog/entry/3969\">codeforces.com</a> instead.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-80382 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-80382 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-80382\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"100542\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/30/2012 06:26\">11 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-100542\" href=\"?#comment-100542\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"100542\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"8\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-100542\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>154A / 155C can also be done in O(N+k) Check out my solution: <a href=\"/contest/154/submission/1950916\" title=\"Посылка 1950916 от ivan100sic\">1950916</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-100542 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-100542 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-100542\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373473\" commentParentId=\"100542\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 14:39\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373473\" href=\"?#comment-373473\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-100542\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373473\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373473\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can someone explain the working of the above solution?I dont get it..</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373473 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373473 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373473\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373480\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 15:31\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373480\" href=\"?#comment-373480\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373480\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373480\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'll do it, I just need to remind myself what I did, it was 5 years ago! :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373480 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373480 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373480\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373488\" commentParentId=\"373473\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ivan100sic\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/26422/avatar/611ce74705dadb74.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/ivan100sic\" title=\"International Grandmaster ivan100sic\" class=\"rated-user user-red\">ivan100sic</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 16:04\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373488\" href=\"?#comment-373488\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373473\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373488\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"26422\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373488\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Here's the idea:</p><p>We split the input string into consecutive maximal substrings of equal or paired elements. Example:</p><p>Pairs are a-b and c-d, the string is "addccbaaebdcdeebabd". The split is: a|ddcc|baa|e|b|dcd|ee|bab|d</p><p>Note that we can now process each substring on its own, without interfering with adjacent substrings. The idea is, if we have a substring containing only type of character, we do not modify it, otherwise we remove all occurrences of the character which appears less often.</p><p>My implementation keeps track of the state (which is one of the paired characters), and the number (c1, c2) of both types of characters within one substring (if there is only one type of character in a group, one of the numbers will be 0). When transitioning from one substring to another, min(c1, c2) is added to the solution.</p><p>Hope this helps!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373488 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373488 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373488\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"373506\" commentParentId=\"373488\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/final_tsu\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/555504/avatar/359a7f4e265e8ded.jpg'/> </a>\n <div><a href=\"/profile/final_tsu\" title=\"Candidate Master final_tsu\" class=\"rated-user user-violet\">final_tsu</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/15/2017 17:13\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-373506\" href=\"?#comment-373506\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-373488\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"373506\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"555504\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-373506\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Ah! I get it now! It's actually a like the solution mentioned in editorial but instead of running through the string k times like the author's solution did,you saved pairs and then did the same thing,reduced complexity to O(n).. Thanks for helping even after 5 years :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-373506 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-373506 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-373506\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"277387\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/ap_hawkdown\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/217627/avatar/6a1d7914a99f9045.jpg'/> </a>\n <div><a href=\"/profile/ap_hawkdown\" title=\"Expert ap_hawkdown\" class=\"rated-user user-blue\">ap_hawkdown</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/07/2016 18:34\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-277387\" href=\"?#comment-277387\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"277387\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"217627\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-277387\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Can anyone explain the kind of Hashing used here <a href=\"//codeforces.com/contest/154/submission/7343162\">http://codeforces.com/contest/154/submission/7343162</a> Here the hash function is allowed to overflow.Can the same kind of hashing be used for strings? Is the one where we use a Modulus more accurate or this one? </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-277387 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-277387 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-277387\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"501368\" commentParentId=\"277387\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/srv_twry\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/447741/avatar/d1a80b00eb029c2b.jpg'/> </a>\n <div><a href=\"/profile/srv_twry\" title=\"Expert srv_twry\" class=\"rated-user user-blue\">srv_twry</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/22/2019 23:51\">5 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-501368\" href=\"?#comment-501368\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-277387\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"501368\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"447741\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-501368\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In this case, overflow acts as modulus with <code>2^64</code>. I think(not sure) it is more accurate since there are fewer chances of hash collisions since I got the wrong answer on test 26 when I used <code>1e9+9</code> for modulo operations in the hash function. <a href=\"https://codeforces.com/contest/155/submission/51729383\">submission</a>. Removing the mod operation and allowing the values to overflow led to an accepted solution. <a href=\"https://codeforces.com/contest/155/submission/51729952\">submission</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-501368 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-501368 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-501368\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"572107\" commentParentId=\"501368\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SLIMSHADYNICK\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/598862/avatar/7629f1b29f0fe807.jpg'/> </a>\n <div><a href=\"/profile/SLIMSHADYNICK\" title=\"Candidate Master SLIMSHADYNICK\" class=\"rated-user user-violet\">SLIMSHADYNICK</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/09/2020 22:01\">4 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-572107\" href=\"?#comment-572107\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-501368\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"572107\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"598862\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-572107\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Did you get the reason why?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-572107 en false\" href=\"#\" 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Message"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Message</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Dr. Moriarty is about to send a message to Sherlock Holmes. He has a string <span class=\"tex-span\"><i>s</i></span>. </p><p>String <span class=\"tex-span\"><i>p</i></span> is called a <span class=\"tex-font-style-it\">substring</span> of string <span class=\"tex-span\"><i>s</i></span> if you can read it starting from some position in the string <span class=\"tex-span\"><i>s</i></span>. For example, string \"<span class=\"tex-font-style-tt\">aba</span>\" has six substrings: \"<span class=\"tex-font-style-tt\">a</span>\", \"<span class=\"tex-font-style-tt\">b</span>\", \"<span class=\"tex-font-style-tt\">a</span>\", \"<span class=\"tex-font-style-tt\">ab</span>\", \"<span class=\"tex-font-style-tt\">ba</span>\", \"<span class=\"tex-font-style-tt\">aba</span>\".</p><p>Dr. Moriarty plans to take string <span class=\"tex-span\"><i>s</i></span> and cut out some substring from it, let's call it <span class=\"tex-span\"><i>t</i></span>. Then he needs to <span class=\"tex-font-style-underline\">change</span> the substring <span class=\"tex-span\"><i>t</i></span> zero or more times. As a result, he should obtain a fixed string <span class=\"tex-span\"><i>u</i></span> (which is the string that should be sent to Sherlock Holmes). One change is defined as making one of the following actions: </p><ul> <li> Insert one letter to any end of the string. </li><li> Delete one letter from any end of the string. </li><li> Change one letter into any other one. </li></ul><p>Moriarty is very smart and after he chooses some substring <span class=\"tex-span\"><i>t</i></span>, he always makes the minimal number of changes to obtain <span class=\"tex-span\"><i>u</i></span>. </p><p>Help Moriarty choose the best substring <span class=\"tex-span\"><i>t</i></span> from all substrings of the string <span class=\"tex-span\"><i>s</i></span>. The substring <span class=\"tex-span\"><i>t</i></span> should minimize the number of changes Moriarty should make to obtain the string <span class=\"tex-span\"><i>u</i></span> from it.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters. The second line contains a non-empty string <span class=\"tex-span\"><i>u</i></span>, consisting of lowercase Latin letters. The lengths of both strings are in the range from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">2000</span>, inclusive.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the only integer — the minimum number of changes that Dr. Moriarty has to make with the string that you choose.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aaaaa<br/>aaa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcabc<br/>bcd<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcdef<br/>klmnopq<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Moriarty can take any substring of length <span class=\"tex-span\">3</span>, and it will be equal to the required message <span class=\"tex-span\"><i>u</i></span>, so Moriarty won't have to make any changes.</p><p>In the second sample you should take a substring consisting of characters from second to fourth (\"<span class=\"tex-font-style-tt\">bca</span>\") or from fifth to sixth (\"<span class=\"tex-font-style-tt\">bc</span>\"). Then you will only have to make one change: to change or to add the last character.</p><p>In the third sample the initial string <span class=\"tex-span\"><i>s</i></span> doesn't contain any character that the message should contain, so, whatever string you choose, you will have to make at least <span class=\"tex-span\">7</span> changes to obtain the required message.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"82e39f99e386d0c21f10caca77c5a792\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"04243fe810274299aeaec00138d6858a44144ca2\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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href=\"https://codeforces.com/blog/entry/3994\" title=\"\" target=\"_blank\">Announcement <span class=\"resource-locale\">(en)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"1147\" resourceName=\"\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"https://codeforces.com/blog/entry/4005\" title=\"Codeforces Round 110 — Разбор задач\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(ru)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"1789\" resourceName=\"Codeforces Round 110 — Разбор задач\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: 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false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_37a7ddd399e88cf606fe60bc5b5a9313abef02c0\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Message</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Dr. Moriarty is about to send a message to Sherlock Holmes. He has a string <span class=\"tex-span\"><i>s</i></span>. </p><p>String <span class=\"tex-span\"><i>p</i></span> is called a <span class=\"tex-font-style-it\">substring</span> of string <span class=\"tex-span\"><i>s</i></span> if you can read it starting from some position in the string <span class=\"tex-span\"><i>s</i></span>. For example, string "<span class=\"tex-font-style-tt\">aba</span>" has six substrings: "<span class=\"tex-font-style-tt\">a</span>", "<span class=\"tex-font-style-tt\">b</span>", "<span class=\"tex-font-style-tt\">a</span>", "<span class=\"tex-font-style-tt\">ab</span>", "<span class=\"tex-font-style-tt\">ba</span>", "<span class=\"tex-font-style-tt\">aba</span>".</p><p>Dr. Moriarty plans to take string <span class=\"tex-span\"><i>s</i></span> and cut out some substring from it, let's call it <span class=\"tex-span\"><i>t</i></span>. Then he needs to <span class=\"tex-font-style-underline\">change</span> the substring <span class=\"tex-span\"><i>t</i></span> zero or more times. As a result, he should obtain a fixed string <span class=\"tex-span\"><i>u</i></span> (which is the string that should be sent to Sherlock Holmes). One change is defined as making one of the following actions: </p><ul> <li> Insert one letter to any end of the string. </li><li> Delete one letter from any end of the string. </li><li> Change one letter into any other one. </li></ul><p>Moriarty is very smart and after he chooses some substring <span class=\"tex-span\"><i>t</i></span>, he always makes the minimal number of changes to obtain <span class=\"tex-span\"><i>u</i></span>. </p><p>Help Moriarty choose the best substring <span class=\"tex-span\"><i>t</i></span> from all substrings of the string <span class=\"tex-span\"><i>s</i></span>. The substring <span class=\"tex-span\"><i>t</i></span> should minimize the number of changes Moriarty should make to obtain the string <span class=\"tex-span\"><i>u</i></span> from it.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters. The second line contains a non-empty string <span class=\"tex-span\"><i>u</i></span>, consisting of lowercase Latin letters. The lengths of both strings are in the range from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">2000</span>, inclusive.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the only integer — the minimum number of changes that Dr. Moriarty has to make with the string that you choose.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aaaaa<br />aaa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcabc<br />bcd<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcdef<br />klmnopq<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Moriarty can take any substring of length <span class=\"tex-span\">3</span>, and it will be equal to the required message <span class=\"tex-span\"><i>u</i></span>, so Moriarty won't have to make any changes.</p><p>In the second sample you should take a substring consisting of characters from second to fourth ("<span class=\"tex-font-style-tt\">bca</span>") or from fifth to sixth ("<span class=\"tex-font-style-tt\">bc</span>"). Then you will only have to make one change: to change or to add the last character.</p><p>In the third sample the initial string <span class=\"tex-span\"><i>s</i></span> doesn't contain any character that the message should contain, so, whatever string you choose, you will have to make at least <span class=\"tex-span\">7</span> changes to obtain the required message.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=A]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Suspects"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Suspects</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating a crime, he identified <span class=\"tex-span\"><i>n</i></span> suspects. He knows for sure that exactly one of them committed the crime. To find out which one did it, the detective lines up the suspects and numbered them from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. After that, he asked each one: \"Which one committed the crime?\". Suspect number <span class=\"tex-span\"><i>i</i></span> answered either \"The crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\", or \"Suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime\". Also, the suspect could say so about himself (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> = <i>i</i></span>).</p><p>Sherlock Holmes understood for sure that exactly <span class=\"tex-span\"><i>m</i></span> answers were the truth and all other answers were a lie. Now help him understand this: which suspect lied and which one told the truth?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ <i>n</i></span>) — the total number of suspects and the number of suspects who told the truth. Next <span class=\"tex-span\"><i>n</i></span> lines contain the suspects' answers. The <span class=\"tex-span\"><i>i</i></span>-th line contains either \"+<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, or \"-<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer, <span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>).</p><p>It is guaranteed that at least one suspect exists, such that if he committed the crime, then exactly <span class=\"tex-span\"><i>m</i></span> people told the truth.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>n</i></span> lines. Line number <span class=\"tex-span\"><i>i</i></span> should contain \"<span class=\"tex-font-style-tt\">Truth</span>\" if suspect number <span class=\"tex-span\"><i>i</i></span> has told the truth for sure. Print \"<span class=\"tex-font-style-tt\">Lie</span>\" if the suspect number <span class=\"tex-span\"><i>i</i></span> lied for sure and print \"<span class=\"tex-font-style-tt\">Not defined</span>\" if he could lie and could tell the truth, too, depending on who committed the crime.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1<br/>+1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Truth<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br/>-1<br/>-2<br/>-3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Not defined<br/>Not defined<br/>Not defined<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br/>+2<br/>-3<br/>+4<br/>-1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Lie<br/>Not defined<br/>Lie<br/>Not defined<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample has the single person and he confesses to the crime, and Sherlock Holmes knows that one person is telling the truth. That means that this person is telling the truth.</p><p>In the second sample there are three suspects and each one denies his guilt. Sherlock Holmes knows that only two of them are telling the truth. Any one of them can be the criminal, so we don't know for any of them, whether this person is telling the truth or not.</p><p>In the third sample the second and the fourth suspect defend the first and the third one. But only one is telling the truth, thus, the first or the third one is the criminal. Both of them can be criminals, so the second and the fourth one can either be lying or telling the truth. The first and the third one are lying for sure as they are blaming the second and the fourth one.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"d94a6a98e890f0719592e1d96b550ba4\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"04243fe810274299aeaec00138d6858a44144ca2\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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class=\"header\"><div class=\"title\">B. Suspects</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating a crime, he identified <span class=\"tex-span\"><i>n</i></span> suspects. He knows for sure that exactly one of them committed the crime. To find out which one did it, the detective lines up the suspects and numbered them from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. After that, he asked each one: "Which one committed the crime?". Suspect number <span class=\"tex-span\"><i>i</i></span> answered either "The crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>", or "Suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime". Also, the suspect could say so about himself (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> = <i>i</i></span>).</p><p>Sherlock Holmes understood for sure that exactly <span class=\"tex-span\"><i>m</i></span> answers were the truth and all other answers were a lie. Now help him understand this: which suspect lied and which one told the truth?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ <i>n</i></span>) — the total number of suspects and the number of suspects who told the truth. Next <span class=\"tex-span\"><i>n</i></span> lines contain the suspects' answers. The <span class=\"tex-span\"><i>i</i></span>-th line contains either "+<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, or "-<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer, <span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>).</p><p>It is guaranteed that at least one suspect exists, such that if he committed the crime, then exactly <span class=\"tex-span\"><i>m</i></span> people told the truth.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>n</i></span> lines. Line number <span class=\"tex-span\"><i>i</i></span> should contain "<span class=\"tex-font-style-tt\">Truth</span>" if suspect number <span class=\"tex-span\"><i>i</i></span> has told the truth for sure. Print "<span class=\"tex-font-style-tt\">Lie</span>" if the suspect number <span class=\"tex-span\"><i>i</i></span> lied for sure and print "<span class=\"tex-font-style-tt\">Not defined</span>" if he could lie and could tell the truth, too, depending on who committed the crime.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1<br />+1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Truth<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br />-1<br />-2<br />-3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Not defined<br />Not defined<br />Not defined<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br />+2<br />-3<br />+4<br />-1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Lie<br />Not defined<br />Lie<br />Not defined<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample has the single person and he confesses to the crime, and Sherlock Holmes knows that one person is telling the truth. That means that this person is telling the truth.</p><p>In the second sample there are three suspects and each one denies his guilt. Sherlock Holmes knows that only two of them are telling the truth. Any one of them can be the criminal, so we don't know for any of them, whether this person is telling the truth or not.</p><p>In the third sample the second and the fourth suspect defend the first and the third one. But only one is telling the truth, thus, the first or the third one is the criminal. Both of them can be criminals, so the second and the fourth one can either be lying or telling the truth. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Cipher"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Cipher</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out to be encrypted. The detective tried really hard to decipher the correspondence, but he couldn't understand anything. </p><p>At last, after some thought, he thought of something. Let's say there is a word <span class=\"tex-span\"><i>s</i></span>, consisting of <span class=\"tex-span\">|<i>s</i>|</span> lowercase Latin letters. Then for one <span class=\"tex-font-style-underline\">operation</span> you can choose a certain position <span class=\"tex-span\"><i>p</i></span> (<span class=\"tex-span\">1 ≤ <i>p</i> < |<i>s</i>|</span>) and perform one of the following actions: </p><ul> <li> either replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it; </li><li> or replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it. </li></ul><p>Let us note that letter \"<span class=\"tex-font-style-tt\">z</span>\" doesn't have a defined following letter and letter \"<span class=\"tex-font-style-tt\">a</span>\" doesn't have a defined preceding letter. That's why the corresponding changes are not acceptable. If the operation requires performing at least one unacceptable change, then such operation cannot be performed.</p><p>Two words <span class=\"tex-font-style-underline\">coincide in their meaning</span> iff one of them can be transformed into the other one as a result of zero or more operations.</p><p>Sherlock Holmes needs to learn to quickly determine the following for each word: how many words can exist that coincide in their meaning with the given word, but differs from the given word in at least one character? Count this number for him modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The input data contains several tests. The first line contains the only integer <span class=\"tex-span\"><i>t</i></span> (<span class=\"tex-span\">1 ≤ <i>t</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of tests.</p><p>Next <span class=\"tex-span\"><i>t</i></span> lines contain the words, one per line. Each word consists of lowercase Latin letters and has length from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>, inclusive. Lengths of words can differ.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each word you should print the number of different <span class=\"tex-font-style-bf\">other</span> words that coincide with it in their meaning — not from the words listed in the input data, but from all possible words. As the sought number can be very large, print its value modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>ab<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>aaaaaaaaaaa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>ya<br/>klmbfxzb<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>24<br/>320092793<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Some explanations about the <span class=\"tex-font-style-underline\">operation</span>:</p><ul> <li> Note that for each letter, we can clearly define the letter that follows it. Letter \"<span class=\"tex-font-style-tt\">b</span>\" alphabetically follows letter \"<span class=\"tex-font-style-tt\">a</span>\", letter \"<span class=\"tex-font-style-tt\">c</span>\" follows letter \"<span class=\"tex-font-style-tt\">b</span>\", ..., \"<span class=\"tex-font-style-tt\">z</span>\" follows letter \"<span class=\"tex-font-style-tt\">y</span>\". </li><li> Preceding letters are defined in the similar manner: letter \"<span class=\"tex-font-style-tt\">y</span>\" precedes letter \"<span class=\"tex-font-style-tt\">z</span>\", ..., \"<span class=\"tex-font-style-tt\">a</span>\" precedes letter \"<span class=\"tex-font-style-tt\">b</span>\". </li><li> Note that the operation never changes a word's length. </li></ul><p>In the first sample you can obtain the only other word \"<span class=\"tex-font-style-tt\">ba</span>\". In the second sample you cannot obtain any other word, so the correct answer is <span class=\"tex-span\">0</span>.</p><p>Consider the third sample. One operation can transform word \"<span class=\"tex-font-style-tt\">klmbfxzb</span>\" into word \"<span class=\"tex-font-style-tt\">klmcexzb</span>\": we should choose <span class=\"tex-span\"><i>p</i> = 4</span>, and replace the fourth letter with the following one (\"<span class=\"tex-font-style-tt\">b</span>\" <span class=\"tex-span\"> → </span> \"<span class=\"tex-font-style-tt\">c</span>\"), and the fifth one — with the preceding one (\"<span class=\"tex-font-style-tt\">f</span>\" <span class=\"tex-span\"> → </span> \"<span class=\"tex-font-style-tt\">e</span>\"). Also, we can obtain many other words from this one. An operation can transform word \"<span class=\"tex-font-style-tt\">ya</span>\" only into one other word \"<span class=\"tex-font-style-tt\">xb</span>\". </p><p>Word \"<span class=\"tex-font-style-tt\">ya</span>\" coincides in its meaning with words \"<span class=\"tex-font-style-tt\">xb</span>\", \"<span class=\"tex-font-style-tt\">wc</span>\", \"<span class=\"tex-font-style-tt\">vd</span>\", ..., \"<span class=\"tex-font-style-tt\">ay</span>\" (overall there are <span class=\"tex-span\">24</span> other words). The word \"<span class=\"tex-font-style-tt\">klmbfxzb</span> has many more variants — there are <span class=\"tex-span\">3320092814</span> other words that coincide with in the meaning. So the answer for the first word equals <span class=\"tex-span\">24</span> and for the second one equals <span class=\"tex-span\">320092793</span> — the number <span class=\"tex-span\">3320092814</span> modulo <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span></p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"4eec5dc49432d19952fec34613561f34\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"04243fe810274299aeaec00138d6858a44144ca2\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_b3ac8b0bc76fc4631e7339b8da26c0aa328b0215\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Cipher</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out to be encrypted. The detective tried really hard to decipher the correspondence, but he couldn't understand anything. </p><p>At last, after some thought, he thought of something. Let's say there is a word <span class=\"tex-span\"><i>s</i></span>, consisting of <span class=\"tex-span\">|<i>s</i>|</span> lowercase Latin letters. Then for one <span class=\"tex-font-style-underline\">operation</span> you can choose a certain position <span class=\"tex-span\"><i>p</i></span> (<span class=\"tex-span\">1 ≤ <i>p</i> < |<i>s</i>|</span>) and perform one of the following actions: </p><ul> <li> either replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it; </li><li> or replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it. </li></ul><p>Let us note that letter "<span class=\"tex-font-style-tt\">z</span>" doesn't have a defined following letter and letter "<span class=\"tex-font-style-tt\">a</span>" doesn't have a defined preceding letter. That's why the corresponding changes are not acceptable. If the operation requires performing at least one unacceptable change, then such operation cannot be performed.</p><p>Two words <span class=\"tex-font-style-underline\">coincide in their meaning</span> iff one of them can be transformed into the other one as a result of zero or more operations.</p><p>Sherlock Holmes needs to learn to quickly determine the following for each word: how many words can exist that coincide in their meaning with the given word, but differs from the given word in at least one character? Count this number for him modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The input data contains several tests. The first line contains the only integer <span class=\"tex-span\"><i>t</i></span> (<span class=\"tex-span\">1 ≤ <i>t</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of tests.</p><p>Next <span class=\"tex-span\"><i>t</i></span> lines contain the words, one per line. Each word consists of lowercase Latin letters and has length from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>, inclusive. Lengths of words can differ.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each word you should print the number of different <span class=\"tex-font-style-bf\">other</span> words that coincide with it in their meaning — not from the words listed in the input data, but from all possible words. As the sought number can be very large, print its value modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />ab<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />aaaaaaaaaaa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />ya<br />klmbfxzb<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>24<br />320092793<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Some explanations about the <span class=\"tex-font-style-underline\">operation</span>:</p><ul> <li> Note that for each letter, we can clearly define the letter that follows it. Letter "<span class=\"tex-font-style-tt\">b</span>" alphabetically follows letter "<span class=\"tex-font-style-tt\">a</span>", letter "<span class=\"tex-font-style-tt\">c</span>" follows letter "<span class=\"tex-font-style-tt\">b</span>", ..., "<span class=\"tex-font-style-tt\">z</span>" follows letter "<span class=\"tex-font-style-tt\">y</span>". </li><li> Preceding letters are defined in the similar manner: letter "<span class=\"tex-font-style-tt\">y</span>" precedes letter "<span class=\"tex-font-style-tt\">z</span>", ..., "<span class=\"tex-font-style-tt\">a</span>" precedes letter "<span class=\"tex-font-style-tt\">b</span>". </li><li> Note that the operation never changes a word's length. </li></ul><p>In the first sample you can obtain the only other word "<span class=\"tex-font-style-tt\">ba</span>". In the second sample you cannot obtain any other word, so the correct answer is <span class=\"tex-span\">0</span>.</p><p>Consider the third sample. One operation can transform word "<span class=\"tex-font-style-tt\">klmbfxzb</span>" into word "<span class=\"tex-font-style-tt\">klmcexzb</span>": we should choose <span class=\"tex-span\"><i>p</i> = 4</span>, and replace the fourth letter with the following one ("<span class=\"tex-font-style-tt\">b</span>" <span class=\"tex-span\"> → </span> "<span class=\"tex-font-style-tt\">c</span>"), and the fifth one — with the preceding one ("<span class=\"tex-font-style-tt\">f</span>" <span class=\"tex-span\"> → </span> "<span class=\"tex-font-style-tt\">e</span>"). Also, we can obtain many other words from this one. An operation can transform word "<span class=\"tex-font-style-tt\">ya</span>" only into one other word "<span class=\"tex-font-style-tt\">xb</span>". </p><p>Word "<span class=\"tex-font-style-tt\">ya</span>" coincides in its meaning with words "<span class=\"tex-font-style-tt\">xb</span>", "<span class=\"tex-font-style-tt\">wc</span>", "<span class=\"tex-font-style-tt\">vd</span>", ..., "<span class=\"tex-font-style-tt\">ay</span>" (overall there are <span class=\"tex-span\">24</span> other words). The word "<span class=\"tex-font-style-tt\">klmbfxzb</span> has many more variants — there are <span class=\"tex-span\">3320092814</span> other words that coincide with in the meaning. So the answer for the first word equals <span class=\"tex-span\">24</span> and for the second one equals <span class=\"tex-span\">320092793</span> — the number <span class=\"tex-span\">3320092814</span> modulo <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span></p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=C]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Clues"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Clues</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating another crime, he found a certain number of clues. Also, he has already found <span class=\"tex-font-style-underline\">direct links</span> between some of those clues. The direct links between the clues are mutual. That is, the direct link between clues <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> and the direct link between clues <span class=\"tex-span\"><i>B</i></span> and <span class=\"tex-span\"><i>A</i></span> is the same thing. No more than one direct link can exist between two clues.</p><p>Of course Sherlock is able to find direct links between all clues. But it will take too much time and the criminals can use this extra time to hide. To solve the crime, Sherlock needs each clue to be linked to all other clues (maybe not directly, via some other clues). Clues <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> are considered linked either if there is a direct link between them or if there is a direct link between <span class=\"tex-span\"><i>A</i></span> and some other clue <span class=\"tex-span\"><i>C</i></span> which is linked to <span class=\"tex-span\"><i>B</i></span>. </p><p>Sherlock Holmes counted the minimum number of additional direct links that he needs to find to solve the crime. As it turns out, it equals <span class=\"tex-span\"><i>T</i></span>.</p><p>Please count the number of different ways to find exactly <span class=\"tex-span\"><i>T</i></span> direct links between the clues so that the crime is solved in the end. Two ways to find direct links are considered different if there exist two clues which have a direct link in one way and do not have a direct link in the other way. </p><p>As the number of different ways can turn out rather big, print it modulo <span class=\"tex-span\"><i>k</i></span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three space-separated integers <span class=\"tex-span\"><i>n</i>, <i>m</i>, <i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the number of clues, the number of direct clue links that Holmes has already found and the divisor for the modulo operation.</p><p>Each of next <span class=\"tex-span\"><i>m</i></span> lines contains two integers <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\">1 ≤ <i>a</i>, <i>b</i> ≤ <i>n</i>, <i>a</i> ≠ <i>b</i></span>), that represent a direct link between clues. It is guaranteed that any two clues are linked by no more than one direct link. Note that the direct links between the clues are mutual.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the answer to the problem modulo <span class=\"tex-span\"><i>k</i></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2 0 1000000000<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0 100<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1 1000000000<br/>1 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>8<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample only has two clues and Sherlock hasn't found any direct link between them yet. The only way to solve the crime is to find the link.</p><p>The second sample has three clues and Sherlock hasn't found any direct links between them. He has to find two of three possible direct links between clues to solve the crime — there are <span class=\"tex-span\">3</span> ways to do it.</p><p>The third sample has four clues and the detective has already found one direct link between the first and the fourth clue. 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_9e4e8cc5b3eba5408368aa803e16ad5ec45de902\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Clues</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating another crime, he found a certain number of clues. Also, he has already found <span class=\"tex-font-style-underline\">direct links</span> between some of those clues. The direct links between the clues are mutual. That is, the direct link between clues <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> and the direct link between clues <span class=\"tex-span\"><i>B</i></span> and <span class=\"tex-span\"><i>A</i></span> is the same thing. No more than one direct link can exist between two clues.</p><p>Of course Sherlock is able to find direct links between all clues. But it will take too much time and the criminals can use this extra time to hide. To solve the crime, Sherlock needs each clue to be linked to all other clues (maybe not directly, via some other clues). Clues <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> are considered linked either if there is a direct link between them or if there is a direct link between <span class=\"tex-span\"><i>A</i></span> and some other clue <span class=\"tex-span\"><i>C</i></span> which is linked to <span class=\"tex-span\"><i>B</i></span>. </p><p>Sherlock Holmes counted the minimum number of additional direct links that he needs to find to solve the crime. As it turns out, it equals <span class=\"tex-span\"><i>T</i></span>.</p><p>Please count the number of different ways to find exactly <span class=\"tex-span\"><i>T</i></span> direct links between the clues so that the crime is solved in the end. Two ways to find direct links are considered different if there exist two clues which have a direct link in one way and do not have a direct link in the other way. </p><p>As the number of different ways can turn out rather big, print it modulo <span class=\"tex-span\"><i>k</i></span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains three space-separated integers <span class=\"tex-span\"><i>n</i>, <i>m</i>, <i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>, <span class=\"tex-span\">1 ≤ <i>k</i> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the number of clues, the number of direct clue links that Holmes has already found and the divisor for the modulo operation.</p><p>Each of next <span class=\"tex-span\"><i>m</i></span> lines contains two integers <span class=\"tex-span\"><i>a</i></span> and <span class=\"tex-span\"><i>b</i></span> (<span class=\"tex-span\">1 ≤ <i>a</i>, <i>b</i> ≤ <i>n</i>, <i>a</i> ≠ <i>b</i></span>), that represent a direct link between clues. It is guaranteed that any two clues are linked by no more than one direct link. Note that the direct links between the clues are mutual.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the answer to the problem modulo <span class=\"tex-span\"><i>k</i></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2 0 1000000000<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 0 100<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1 1000000000<br />1 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>8<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample only has two clues and Sherlock hasn't found any direct link between them yet. The only way to solve the crime is to find the link.</p><p>The second sample has three clues and Sherlock hasn't found any direct links between them. He has to find two of three possible direct links between clues to solve the crime — there are <span class=\"tex-span\">3</span> ways to do it.</p><p>The third sample has four clues and the detective has already found one direct link between the first and the fourth clue. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Mrs. Hudson's Pancakes"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Mrs. Hudson's Pancakes</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Mrs. Hudson hasn't made her famous pancakes for quite a while and finally she decided to make them again. She has learned <span class=\"tex-span\"><i>m</i></span> new recipes recently and she can't wait to try them. Those recipes are based on <span class=\"tex-span\"><i>n</i></span> special spices. Mrs. Hudson has these spices in the kitchen lying in jars <span class=\"tex-font-style-bf\">numbered</span> with integers from <span class=\"tex-span\">0</span> to <span class=\"tex-span\"><i>n</i> - 1</span> (each spice lies in an individual jar). Each jar also has the <span class=\"tex-font-style-bf\">price</span> of the corresponding spice inscribed — some integer <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>We know three values for the <span class=\"tex-span\"><i>i</i></span>-th pancake recipe: <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>. Here <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> are integers, and <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> is the <span class=\"tex-font-style-underline\">pattern</span> of some integer written in the numeral system with radix <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>. The pattern contains digits, Latin letters (to denote digits larger than nine) and question marks. Number <span class=\"tex-span\"><i>x</i></span> in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system <span class=\"tex-font-style-underline\">matches the pattern</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>, if we can replace question marks in the pattern with digits and letters so that we obtain number <span class=\"tex-span\"><i>x</i></span> (leading zeroes aren't taken into consideration when performing the comparison). More formally: each question mark should be replaced by exactly one digit or exactly one letter. If after we replace all question marks we get a number with leading zeroes, we can delete these zeroes. For example, number <span class=\"tex-font-style-tt\">40A9875</span> in the <span class=\"tex-span\">11</span>-base numeral system matches the pattern \"<span class=\"tex-font-style-tt\">??4??987?</span>\", and number <span class=\"tex-font-style-tt\">4A9875</span> does not.</p><p>To make the pancakes by the <span class=\"tex-span\"><i>i</i></span>-th recipe, Mrs. Hudson should take all jars with <span class=\"tex-font-style-bf\">numbers</span> whose representation in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system matches the pattern <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>. The <span class=\"tex-font-style-underline\">control number</span> of the recipe (<span class=\"tex-span\"><i>z</i><sub class=\"lower-index\"><i>i</i></sub></span>) is defined as the sum of number <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and the product of <span class=\"tex-font-style-bf\">prices</span> of all taken jars. More formally: <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/86ea62c3906295d11ece4457098162f25554cfce.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/> (where <span class=\"tex-span\"><i>j</i></span> is all such numbers whose representation in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system matches the pattern <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>).</p><p>Mrs. Hudson isn't as interested in the control numbers as she is in their minimum prime divisors. Your task is: for each recipe <span class=\"tex-span\"><i>i</i></span> find the minimum prime divisor of number <span class=\"tex-span\"><i>z</i><sub class=\"lower-index\"><i>i</i></sub></span>. If this divisor exceeds <span class=\"tex-span\">100</span>, then you do not have to find it, print -1.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">4</sup></span>). The second line contains space-separated prices of the spices <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">0</sub>, <i>a</i><sub class=\"lower-index\">1</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i> - 1</sub></span>, where <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">18</sup></span>).</p><p>The third line contains the single integer <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>m</i> ≤ 3·10<sup class=\"upper-index\">4</sup></span>) — the number of recipes Mrs. Hudson has learned. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines describe the recipes, one per line. First you are given an integer <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, written in the decimal numeral system (<span class=\"tex-span\">2 ≤ <i>d</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 16</span>). Then after a space follows the <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> pattern — a string from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">30</span> in length, inclusive, consisting of digits from \"<span class=\"tex-font-style-tt\">0</span>\" to \"<span class=\"tex-font-style-tt\">9</span>\", letters from \"<span class=\"tex-font-style-tt\">A</span>\" to \"<span class=\"tex-font-style-tt\">F</span>\" and signs \"<span class=\"tex-font-style-tt\">?</span>\". Letters from \"<span class=\"tex-font-style-tt\">A</span>\" to \"<span class=\"tex-font-style-tt\">F</span>\" should be considered as digits from <span class=\"tex-span\">10</span> to <span class=\"tex-span\">15</span> correspondingly. It is guaranteed that all digits of the pattern (including the digits that are represented by letters) are strictly less than <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>. Then after a space follows an integer <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>, written in the decimal numeral system (<span class=\"tex-span\">1 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">18</sup></span>).</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++, in is preferred to use <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span>, strings or the <span class=\"tex-font-style-tt\">%I64d</span> specificator instead.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each recipe count by what minimum prime number the control number is divided and print this prime number on the single line. If this number turns out larger than <span class=\"tex-span\">100</span>, print -1.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>1<br/>1<br/>2 ? 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br/>2 3 5 7<br/>4<br/>2 ?0 11<br/>2 ?1 13<br/>2 0? 17<br/>2 1? 19<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br/>2<br/>23<br/>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>1000000000000000000<br/>1<br/>16 ?????????????? 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>-1<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test any one-digit number in the binary system matches. The jar is only one and its price is equal to <span class=\"tex-span\">1</span>, the number <span class=\"tex-span\"><i>c</i></span> is also equal to <span class=\"tex-span\">1</span>, the control number equals <span class=\"tex-span\">2</span>. The minimal prime divisor of <span class=\"tex-span\">2</span> is <span class=\"tex-span\">2</span>.</p><p>In the second test there are <span class=\"tex-span\">4</span> jars with numbers from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">3</span>, and the prices are equal <span class=\"tex-span\">2</span>, <span class=\"tex-span\">3</span>, <span class=\"tex-span\">5</span> and <span class=\"tex-span\">7</span> correspondingly — the first four prime numbers. In all recipes numbers should be two-digit. In the first recipe the second digit always is <span class=\"tex-span\">0</span>, in the second recipe the second digit always is <span class=\"tex-span\">1</span>, in the third recipe the first digit must be <span class=\"tex-span\">0</span>, in the fourth recipe the first digit always is <span class=\"tex-span\">1</span>. Consequently, the control numbers are as follows: in the first recipe <span class=\"tex-span\">2 × 5 + 11 = 21</span> (the minimum prime divisor is <span class=\"tex-span\">3</span>), in the second recipe <span class=\"tex-span\">3 × 7 + 13 = 44</span> (the minimum prime divisor is <span class=\"tex-span\">2</span>), in the third recipe <span class=\"tex-span\">2 × 3 + 17 = 23</span> (the minimum prime divisor is <span class=\"tex-span\">23</span>) and, finally, in the fourth recipe <span class=\"tex-span\">5 × 7 + 19 = 54</span> (the minimum prime divisor is <span class=\"tex-span\">2</span>).</p><p>In the third test, the number should consist of fourteen digits and be recorded in a sixteen-base numeral system. Number <span class=\"tex-span\">0</span> (the number of the single bottles) matches, the control number will be equal to <span class=\"tex-span\">10<sup class=\"upper-index\">18</sup> + 1</span>. The minimum prime divisor of this number is equal to <span class=\"tex-span\">101</span> and you should print -1.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"b176faf890e8c1ddba40a77ad7cde57a\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"04243fe810274299aeaec00138d6858a44144ca2\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/156\">Codeforces Round 110 (Div. 1)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='b176faf890e8c1ddba40a77ad7cde57a'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/156/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Brute force\">\r\n brute force\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Dynamic programming\">\r\n dp\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *3000\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='b176faf890e8c1ddba40a77ad7cde57a'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"963\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='b176faf890e8c1ddba40a77ad7cde57a'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"963\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"https://codeforces.com/blog/entry/3994\" title=\"\" target=\"_blank\">Announcement <span class=\"resource-locale\">(en)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"1147\" resourceName=\"\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"https://codeforces.com/blog/entry/4005\" title=\"Codeforces Round 110 — Разбор задач\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(ru)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"1789\" resourceName=\"Codeforces Round 110 — Разбор задач\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/156\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/156/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/156/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/156/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/156/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/156/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/156/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/156/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"E\" data-uuid=\"ps_4c420401cbd2f5b9f288e72f663644867412a75e\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Mrs. Hudson's Pancakes</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Mrs. Hudson hasn't made her famous pancakes for quite a while and finally she decided to make them again. She has learned <span class=\"tex-span\"><i>m</i></span> new recipes recently and she can't wait to try them. Those recipes are based on <span class=\"tex-span\"><i>n</i></span> special spices. Mrs. Hudson has these spices in the kitchen lying in jars <span class=\"tex-font-style-bf\">numbered</span> with integers from <span class=\"tex-span\">0</span> to <span class=\"tex-span\"><i>n</i> - 1</span> (each spice lies in an individual jar). Each jar also has the <span class=\"tex-font-style-bf\">price</span> of the corresponding spice inscribed — some integer <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>We know three values for the <span class=\"tex-span\"><i>i</i></span>-th pancake recipe: <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>. Here <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> are integers, and <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> is the <span class=\"tex-font-style-underline\">pattern</span> of some integer written in the numeral system with radix <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>. The pattern contains digits, Latin letters (to denote digits larger than nine) and question marks. Number <span class=\"tex-span\"><i>x</i></span> in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system <span class=\"tex-font-style-underline\">matches the pattern</span> <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>, if we can replace question marks in the pattern with digits and letters so that we obtain number <span class=\"tex-span\"><i>x</i></span> (leading zeroes aren't taken into consideration when performing the comparison). More formally: each question mark should be replaced by exactly one digit or exactly one letter. If after we replace all question marks we get a number with leading zeroes, we can delete these zeroes. For example, number <span class=\"tex-font-style-tt\">40A9875</span> in the <span class=\"tex-span\">11</span>-base numeral system matches the pattern "<span class=\"tex-font-style-tt\">??4??987?</span>", and number <span class=\"tex-font-style-tt\">4A9875</span> does not.</p><p>To make the pancakes by the <span class=\"tex-span\"><i>i</i></span>-th recipe, Mrs. Hudson should take all jars with <span class=\"tex-font-style-bf\">numbers</span> whose representation in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system matches the pattern <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>. The <span class=\"tex-font-style-underline\">control number</span> of the recipe (<span class=\"tex-span\"><i>z</i><sub class=\"lower-index\"><i>i</i></sub></span>) is defined as the sum of number <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and the product of <span class=\"tex-font-style-bf\">prices</span> of all taken jars. More formally: <img align=\"middle\" class=\"tex-formula\" src=\"https://espresso.codeforces.com/86ea62c3906295d11ece4457098162f25554cfce.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> (where <span class=\"tex-span\"><i>j</i></span> is all such numbers whose representation in the <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>-base numeral system matches the pattern <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>).</p><p>Mrs. Hudson isn't as interested in the control numbers as she is in their minimum prime divisors. Your task is: for each recipe <span class=\"tex-span\"><i>i</i></span> find the minimum prime divisor of number <span class=\"tex-span\"><i>z</i><sub class=\"lower-index\"><i>i</i></sub></span>. If this divisor exceeds <span class=\"tex-span\">100</span>, then you do not have to find it, print -1.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">4</sup></span>). The second line contains space-separated prices of the spices <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">0</sub>, <i>a</i><sub class=\"lower-index\">1</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i> - 1</sub></span>, where <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">18</sup></span>).</p><p>The third line contains the single integer <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>m</i> ≤ 3·10<sup class=\"upper-index\">4</sup></span>) — the number of recipes Mrs. Hudson has learned. </p><p>Next <span class=\"tex-span\"><i>m</i></span> lines describe the recipes, one per line. First you are given an integer <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, written in the decimal numeral system (<span class=\"tex-span\">2 ≤ <i>d</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 16</span>). Then after a space follows the <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> pattern — a string from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">30</span> in length, inclusive, consisting of digits from "<span class=\"tex-font-style-tt\">0</span>" to "<span class=\"tex-font-style-tt\">9</span>", letters from "<span class=\"tex-font-style-tt\">A</span>" to "<span class=\"tex-font-style-tt\">F</span>" and signs "<span class=\"tex-font-style-tt\">?</span>". Letters from "<span class=\"tex-font-style-tt\">A</span>" to "<span class=\"tex-font-style-tt\">F</span>" should be considered as digits from <span class=\"tex-span\">10</span> to <span class=\"tex-span\">15</span> correspondingly. It is guaranteed that all digits of the pattern (including the digits that are represented by letters) are strictly less than <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>. Then after a space follows an integer <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>, written in the decimal numeral system (<span class=\"tex-span\">1 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">18</sup></span>).</p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++, in is preferred to use <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span>, strings or the <span class=\"tex-font-style-tt\">%I64d</span> specificator instead.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each recipe count by what minimum prime number the control number is divided and print this prime number on the single line. If this number turns out larger than <span class=\"tex-span\">100</span>, print -1.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />1<br />1<br />2 ? 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br />2 3 5 7<br />4<br />2 ?0 11<br />2 ?1 13<br />2 0? 17<br />2 1? 19<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3<br />2<br />23<br />2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />1000000000000000000<br />1<br />16 ?????????????? 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>-1<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test any one-digit number in the binary system matches. The jar is only one and its price is equal to <span class=\"tex-span\">1</span>, the number <span class=\"tex-span\"><i>c</i></span> is also equal to <span class=\"tex-span\">1</span>, the control number equals <span class=\"tex-span\">2</span>. The minimal prime divisor of <span class=\"tex-span\">2</span> is <span class=\"tex-span\">2</span>.</p><p>In the second test there are <span class=\"tex-span\">4</span> jars with numbers from <span class=\"tex-span\">0</span> to <span class=\"tex-span\">3</span>, and the prices are equal <span class=\"tex-span\">2</span>, <span class=\"tex-span\">3</span>, <span class=\"tex-span\">5</span> and <span class=\"tex-span\">7</span> correspondingly — the first four prime numbers. In all recipes numbers should be two-digit. In the first recipe the second digit always is <span class=\"tex-span\">0</span>, in the second recipe the second digit always is <span class=\"tex-span\">1</span>, in the third recipe the first digit must be <span class=\"tex-span\">0</span>, in the fourth recipe the first digit always is <span class=\"tex-span\">1</span>. Consequently, the control numbers are as follows: in the first recipe <span class=\"tex-span\">2 × 5 + 11 = 21</span> (the minimum prime divisor is <span class=\"tex-span\">3</span>), in the second recipe <span class=\"tex-span\">3 × 7 + 13 = 44</span> (the minimum prime divisor is <span class=\"tex-span\">2</span>), in the third recipe <span class=\"tex-span\">2 × 3 + 17 = 23</span> (the minimum prime divisor is <span class=\"tex-span\">23</span>) and, finally, in the fourth recipe <span class=\"tex-span\">5 × 7 + 19 = 54</span> (the minimum prime divisor is <span class=\"tex-span\">2</span>).</p><p>In the third test, the number should consist of fourteen digits and be recorded in a sixteen-base numeral system. Number <span class=\"tex-span\">0</span> (the number of the single bottles) matches, the control number will be equal to <span class=\"tex-span\">10<sup class=\"upper-index\">18</sup> + 1</span>. The minimum prime divisor of this number is equal to <span class=\"tex-span\">101</span> and you should print -1.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=E]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n $problem.find(\"a.view-changes\").click(function() {\r\n $.post(\"/data/diff\", {action: \"getDiff\", a: previousStatementText, b: statementText}, function (result) {\r\n if (result[\"success\"] 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dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Game Outcome"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Game Outcome</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes and Dr. Watson played some game on a checkered board <span class=\"tex-span\"><i>n</i> × <i>n</i></span> in size. During the game they put numbers on the board's squares by some tricky rules we don't know. However, the game is now over and each square of the board contains exactly one number. To understand who has won, they need to count the number of <span class=\"tex-font-style-underline\">winning</span> squares. To determine if the particular square is winning you should do the following. Calculate the sum of all numbers on the squares that share this column (including the given square) and separately calculate the sum of all numbers on the squares that share this row (including the given square). A square is considered <span class=\"tex-font-style-underline\">winning</span> if the sum of the column numbers is <span class=\"tex-font-style-bf\">strictly</span> greater than the sum of the row numbers.</p><center><img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/5f4f91a40be4f875bdd75333c3e82c331f09d293.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/></center><p>For instance, lets game was ended like is shown in the picture. Then the purple cell is winning, because the sum of its column numbers equals <span class=\"tex-span\">8 + 3 + 6 + 7 = 24</span>, sum of its row numbers equals <span class=\"tex-span\">9 + 5 + 3 + 2 = 19</span>, and <span class=\"tex-span\">24 > 19</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 30</span>). Each of the following <span class=\"tex-span\"><i>n</i></span> lines contain <span class=\"tex-span\"><i>n</i></span> space-separated integers. The <span class=\"tex-span\"><i>j</i></span>-th number on the <span class=\"tex-span\"><i>i</i></span>-th line represents the number on the square that belongs to the <span class=\"tex-span\"><i>j</i></span>-th column and the <span class=\"tex-span\"><i>i</i></span>-th row on the board. All number on the board are integers from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of the winning squares.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>1 2<br/>3 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br/>5 7 8 4<br/>9 5 3 2<br/>1 6 6 4<br/>9 5 7 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first example two upper squares are winning.</p><p>In the third example three left squares in the both middle rows are winning:</p><pre class=\"verbatim\">5 7 8 4<br/><span class=\"tex-font-style-bf\"><span class=\"tex-font-style-underline\"><span class=\"tex-span\">9</span> <span class=\"tex-span\">5</span> <span class=\"tex-span\">3</span></span></span> 2<br/><span class=\"tex-font-style-bf\"><span class=\"tex-font-style-underline\"><span class=\"tex-span\">1</span> <span class=\"tex-span\">6</span> <span class=\"tex-span\">6</span></span></span> 4<br/>9 5 7 3<br/></pre></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"ff241a6e62fa81d98b534e78096cda44\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"6e2aa082339bb3ec1a1fdae893dc4a0b46db4272\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/157\">Codeforces Round 110 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? Just register for practice and you will be able to submit solutions.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"\" method=\"post\"><input type='hidden' name='csrf_token' value='ff241a6e62fa81d98b534e78096cda44'/>\r\n <input type=\"hidden\" name=\"action\" value=\"registerForPractice\"/>\r\n <input type=\"submit\" name=\"submit\" value=\"Register for practice\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div> \r\n</div>\r\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox ContestVirtualFrame borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Virtual participation <i class=\"sidebar-caption-icon las la-angle-down\"></i>\r\n\n <div class=\"top-links\">\n </div>\n </div>\n<div style=\" \"\r\n\r\n data-page-url=\"/data/sidebarFrames\"\r\n\r\n>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/157/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Brute force\">\r\n brute force\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *800\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='ff241a6e62fa81d98b534e78096cda44'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"964\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='ff241a6e62fa81d98b534e78096cda44'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"964\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3994\" title=\"Codeforces Round 110\" target=\"_blank\">Codeforces Round 110</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"373:374\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4005\" title=\"Codeforces Round 110 — Разбор задач\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(ru)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"954\" resourceName=\"Codeforces Round 110 — Разбор задач\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/157\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/157/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/157/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/157/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/157/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/157/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/157/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/157/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 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class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Game Outcome</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes and Dr. Watson played some game on a checkered board <span class=\"tex-span\"><i>n</i> × <i>n</i></span> in size. During the game they put numbers on the board's squares by some tricky rules we don't know. However, the game is now over and each square of the board contains exactly one number. To understand who has won, they need to count the number of <span class=\"tex-font-style-underline\">winning</span> squares. To determine if the particular square is winning you should do the following. Calculate the sum of all numbers on the squares that share this column (including the given square) and separately calculate the sum of all numbers on the squares that share this row (including the given square). A square is considered <span class=\"tex-font-style-underline\">winning</span> if the sum of the column numbers is <span class=\"tex-font-style-bf\">strictly</span> greater than the sum of the row numbers.</p><center><img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/5f4f91a40be4f875bdd75333c3e82c331f09d293.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /></center><p>For instance, lets game was ended like is shown in the picture. Then the purple cell is winning, because the sum of its column numbers equals <span class=\"tex-span\">8 + 3 + 6 + 7 = 24</span>, sum of its row numbers equals <span class=\"tex-span\">9 + 5 + 3 + 2 = 19</span>, and <span class=\"tex-span\">24 > 19</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 30</span>). Each of the following <span class=\"tex-span\"><i>n</i></span> lines contain <span class=\"tex-span\"><i>n</i></span> space-separated integers. The <span class=\"tex-span\"><i>j</i></span>-th number on the <span class=\"tex-span\"><i>i</i></span>-th line represents the number on the square that belongs to the <span class=\"tex-span\"><i>j</i></span>-th column and the <span class=\"tex-span\"><i>i</i></span>-th row on the board. All number on the board are integers from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the number of the winning squares.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />1 2<br />3 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br />5 7 8 4<br />9 5 3 2<br />1 6 6 4<br />9 5 7 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first example two upper squares are winning.</p><p>In the third example three left squares in the both middle rows are winning:</p><pre class=\"verbatim\">5 7 8 4<br /><span class=\"tex-font-style-bf\"><span class=\"tex-font-style-underline\"><span class=\"tex-span\">9</span> <span class=\"tex-span\">5</span> <span class=\"tex-span\">3</span></span></span> 2<br /><span class=\"tex-font-style-bf\"><span class=\"tex-font-style-underline\"><span class=\"tex-span\">1</span> <span class=\"tex-span\">6</span> <span class=\"tex-span\">6</span></span></span> 4<br />9 5 7 3<br /></pre></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=A]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if 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dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. 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Trace"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Trace</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day, as Sherlock Holmes was tracking down one very important criminal, he found a wonderful painting on the wall. This wall could be represented as a plane. The painting had several concentric circles that divided the wall into several parts. Some parts were painted red and all the other were painted blue. Besides, any two neighboring parts were painted different colors, that is, the red and the blue color were alternating, i. e. followed one after the other. The outer area of the wall (the area that lied outside all circles) was painted blue. Help Sherlock Holmes determine the total area of red parts of the wall.</p><p><span class=\"tex-font-style-underline\">Let us remind you that two circles are called concentric if their centers coincide. Several circles are called concentric if any two of them are concentric.</span></p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>). The second line contains <span class=\"tex-span\"><i>n</i></span> space-separated integers <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>r</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>) — the circles' radii. It is guaranteed that all circles are different.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — total area of the part of the wall that is painted red. The answer is accepted if absolute or relative error doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 4</sup></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3.1415926536<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br/>1 4 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>40.8407044967<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the picture is just one circle of radius <span class=\"tex-span\">1</span>. Inner part of the circle is painted red. The area of the red part equals <span class=\"tex-span\">π × 1<sup class=\"upper-index\">2</sup> = π</span>.</p><p>In the second sample there are three circles of radii <span class=\"tex-span\">1</span>, <span class=\"tex-span\">4</span> and <span class=\"tex-span\">2</span>. Outside part of the second circle is painted blue. Part between the second and the third circles is painted red. Part between the first and the third is painted blue. And, finally, the inner part of the first circle is painted red. Overall there are two red parts: the ring between the second and the third circles and the inner part of the first circle. Total area of the red parts is equal <span class=\"tex-span\">(π × 4<sup class=\"upper-index\">2</sup> - π × 2<sup class=\"upper-index\">2</sup>) + π × 1<sup class=\"upper-index\">2</sup> = π × 12 + π = 13π</span></p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"7d92877e3879bee490adf55f26fc9e8d\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"6e2aa082339bb3ec1a1fdae893dc4a0b46db4272\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/157\">Codeforces Round 110 (Div. 2)</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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It is supported only ICPC mode for virtual contests.\n\nIf you've seen these problems, a virtual contest is not for you - solve these problems in the archive.\n\nIf you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.\n\nNever use someone else's code, read the tutorials or communicate with other person during a virtual contest.\r\n </div>\r\n\r\n <div style=\"text-align:center;margin:1em;\">\r\n <form action=\"/contest/157/virtual\" method=\"get\">\r\n <input type=\"submit\" name=\"submit\" value=\"Start virtual contest\" style=\"padding:0 0.5em;\">\r\n </form>\r\n </div>\r\n</div>\r\n <script>\r\n $(function () {\r\n $(\".ContestVirtualFrame .sidebar-caption-icon\").click(function() {\r\n $(this).toggleClass(\"la-angle-down la-angle-right\");\r\n const $target = $(this).parent().next();\r\n $target.toggle();\r\n const dataPageUrl = $target.attr(\"data-page-url\");\r\n const collapsed = 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Geometry, computational geometry\">\r\n geometry\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Sortings, orderings\">\r\n sortings\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *1000\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='7d92877e3879bee490adf55f26fc9e8d'/>\r\n <input name=\"action\" type=\"hidden\" value=\"addTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"965\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<form id=\"removeTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' value='7d92877e3879bee490adf55f26fc9e8d'/>\r\n <input name=\"action\" type=\"hidden\" value=\"removeTag\"/>\r\n <input name=\"problemId\" type=\"hidden\" value=\"965\"/>\r\n <input name=\"tagName\" type=\"hidden\" value=\"\"/>\r\n</form>\r\n\r\n<script type=\"text/javascript\">\r\n $(\".tag-box img\").click(function () {\r\n var tagName = $(this).attr(\"value\");\r\n Codeforces.confirm(\"Are you sure you want to remove this tag?\", function () {\r\n $(\"#removeTagForm input[name=tagName]\").val(tagName);\r\n $(\"#removeTagForm\").submit();\r\n }, function () {\r\n }, \"Yes\", \"No\");\r\n });\r\n\r\n $(\"#addTagLink\").click(function () {\r\n $(this).hide();\r\n $(\"#addTagLabel\").show();\r\n return false;\r\n });\r\n\r\n $(\"#addTagSelect\").change(function () {\r\n var tagName = $(this).val();\r\n if (tagName === \"\") {\r\n $(\"#addTagLabel\").hide();\r\n $(\"#addTagLink\").show();\r\n } else {\r\n $(\"#addTagForm input[name=tagName]\").val(tagName);\r\n $(\"#addTagForm\").submit();\r\n }\r\n });\r\n</script>\r\n\r\n<style type=\"text/css\">\r\n#new-resource-form tr td {\r\npadding-top: 0.5em;\r\n}\r\n#new-resource-form input:not([type=\"submit\"]) {\r\nfont-size: 0.8em;\r\n}\r\n#new-resource-form select {\r\nfont-size: 0.8em;\r\n}\r\n.new-resource-error {\r\nfont-size: 0.8em;\r\n}\r\n.resource-locale {\r\ncolor: #666;\r\nfont-family: Consolas, \"Andale Mono WT\", \"Andale Mono\", \"Lucida Console\", \"Lucida Sans Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/3994\" title=\"Codeforces Round 110\" target=\"_blank\">Codeforces Round 110</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"373:374\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4005\" title=\"Codeforces Round 110 — Разбор задач\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(ru)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"954\" resourceName=\"Codeforces Round 110 — Разбор задач\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/157\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/157/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/157/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/157/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/157/hacks\">Hacks</a></li>\r\n <li><a\r\n href=\"/contest/157/room/1\">Room</a></li>\r\n <li><a\r\n href=\"/contest/157/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/157/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const nodeToText = function (node, pre) {\r\n let result = [];\r\n\r\n if (node.tagName === \"SCRIPT\" || node.tagName === \"math\"\r\n || (node.classList && node.classList.contains(\"input-output-copier\")))\r\n return [];\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(OPENING_SPACE);\r\n }\r\n\r\n if (node.nodeType === Node.TEXT_NODE) {\r\n let s = node.textContent;\r\n if (!pre) {\r\n s = s.replace(/\\s+/g, \" \");\r\n }\r\n if (s.length > 0) {\r\n result.push(s);\r\n }\r\n }\r\n\r\n if (pre && node.tagName === \"BR\") {\r\n result.push(\"\\n\");\r\n }\r\n\r\n node.childNodes.forEach(function (child) {\r\n result.push(nodeToText(child, node.tagName === \"PRE\").join(\"\"));\r\n });\r\n\r\n if (node.tagName === \"DIV\"\r\n || node.tagName === \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_97b3115f59adc9ea64d7cfb97723b931775c62b5\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Trace</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One day, as Sherlock Holmes was tracking down one very important criminal, he found a wonderful painting on the wall. This wall could be represented as a plane. The painting had several concentric circles that divided the wall into several parts. Some parts were painted red and all the other were painted blue. Besides, any two neighboring parts were painted different colors, that is, the red and the blue color were alternating, i. e. followed one after the other. The outer area of the wall (the area that lied outside all circles) was painted blue. Help Sherlock Holmes determine the total area of red parts of the wall.</p><p><span class=\"tex-font-style-underline\">Let us remind you that two circles are called concentric if their centers coincide. Several circles are called concentric if any two of them are concentric.</span></p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>). The second line contains <span class=\"tex-span\"><i>n</i></span> space-separated integers <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>r</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>) — the circles' radii. It is guaranteed that all circles are different.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single real number — total area of the part of the wall that is painted red. The answer is accepted if absolute or relative error doesn't exceed <span class=\"tex-span\">10<sup class=\"upper-index\"> - 4</sup></span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3.1415926536<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br />1 4 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>40.8407044967<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the picture is just one circle of radius <span class=\"tex-span\">1</span>. Inner part of the circle is painted red. The area of the red part equals <span class=\"tex-span\">π × 1<sup class=\"upper-index\">2</sup> = π</span>.</p><p>In the second sample there are three circles of radii <span class=\"tex-span\">1</span>, <span class=\"tex-span\">4</span> and <span class=\"tex-span\">2</span>. Outside part of the second circle is painted blue. Part between the second and the third circles is painted red. Part between the first and the third is painted blue. And, finally, the inner part of the first circle is painted red. Overall there are two red parts: the ring between the second and the third circles and the inner part of the first circle. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Message"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Message</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Dr. Moriarty is about to send a message to Sherlock Holmes. He has a string <span class=\"tex-span\"><i>s</i></span>. </p><p>String <span class=\"tex-span\"><i>p</i></span> is called a <span class=\"tex-font-style-it\">substring</span> of string <span class=\"tex-span\"><i>s</i></span> if you can read it starting from some position in the string <span class=\"tex-span\"><i>s</i></span>. For example, string \"<span class=\"tex-font-style-tt\">aba</span>\" has six substrings: \"<span class=\"tex-font-style-tt\">a</span>\", \"<span class=\"tex-font-style-tt\">b</span>\", \"<span class=\"tex-font-style-tt\">a</span>\", \"<span class=\"tex-font-style-tt\">ab</span>\", \"<span class=\"tex-font-style-tt\">ba</span>\", \"<span class=\"tex-font-style-tt\">aba</span>\".</p><p>Dr. Moriarty plans to take string <span class=\"tex-span\"><i>s</i></span> and cut out some substring from it, let's call it <span class=\"tex-span\"><i>t</i></span>. Then he needs to <span class=\"tex-font-style-underline\">change</span> the substring <span class=\"tex-span\"><i>t</i></span> zero or more times. As a result, he should obtain a fixed string <span class=\"tex-span\"><i>u</i></span> (which is the string that should be sent to Sherlock Holmes). One change is defined as making one of the following actions: </p><ul> <li> Insert one letter to any end of the string. </li><li> Delete one letter from any end of the string. </li><li> Change one letter into any other one. </li></ul><p>Moriarty is very smart and after he chooses some substring <span class=\"tex-span\"><i>t</i></span>, he always makes the minimal number of changes to obtain <span class=\"tex-span\"><i>u</i></span>. </p><p>Help Moriarty choose the best substring <span class=\"tex-span\"><i>t</i></span> from all substrings of the string <span class=\"tex-span\"><i>s</i></span>. The substring <span class=\"tex-span\"><i>t</i></span> should minimize the number of changes Moriarty should make to obtain the string <span class=\"tex-span\"><i>u</i></span> from it.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters. The second line contains a non-empty string <span class=\"tex-span\"><i>u</i></span>, consisting of lowercase Latin letters. The lengths of both strings are in the range from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">2000</span>, inclusive.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the only integer — the minimum number of changes that Dr. Moriarty has to make with the string that you choose.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aaaaa<br/>aaa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcabc<br/>bcd<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcdef<br/>klmnopq<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Moriarty can take any substring of length <span class=\"tex-span\">3</span>, and it will be equal to the required message <span class=\"tex-span\"><i>u</i></span>, so Moriarty won't have to make any changes.</p><p>In the second sample you should take a substring consisting of characters from second to fourth (\"<span class=\"tex-font-style-tt\">bca</span>\") or from fifth to sixth (\"<span class=\"tex-font-style-tt\">bc</span>\"). Then you will only have to make one change: to change or to add the last character.</p><p>In the third sample the initial string <span class=\"tex-span\"><i>s</i></span> doesn't contain any character that the message should contain, so, whatever string you choose, you will have to make at least <span class=\"tex-span\">7</span> changes to obtain the required message.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"9ec3c22db907b3bb3a62346326fcea85\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"6e2aa082339bb3ec1a1fdae893dc4a0b46db4272\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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}\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_feb27d950b7b84344a0cb1b7d060a4eaae1ad471\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Message</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Dr. Moriarty is about to send a message to Sherlock Holmes. He has a string <span class=\"tex-span\"><i>s</i></span>. </p><p>String <span class=\"tex-span\"><i>p</i></span> is called a <span class=\"tex-font-style-it\">substring</span> of string <span class=\"tex-span\"><i>s</i></span> if you can read it starting from some position in the string <span class=\"tex-span\"><i>s</i></span>. For example, string "<span class=\"tex-font-style-tt\">aba</span>" has six substrings: "<span class=\"tex-font-style-tt\">a</span>", "<span class=\"tex-font-style-tt\">b</span>", "<span class=\"tex-font-style-tt\">a</span>", "<span class=\"tex-font-style-tt\">ab</span>", "<span class=\"tex-font-style-tt\">ba</span>", "<span class=\"tex-font-style-tt\">aba</span>".</p><p>Dr. Moriarty plans to take string <span class=\"tex-span\"><i>s</i></span> and cut out some substring from it, let's call it <span class=\"tex-span\"><i>t</i></span>. Then he needs to <span class=\"tex-font-style-underline\">change</span> the substring <span class=\"tex-span\"><i>t</i></span> zero or more times. As a result, he should obtain a fixed string <span class=\"tex-span\"><i>u</i></span> (which is the string that should be sent to Sherlock Holmes). One change is defined as making one of the following actions: </p><ul> <li> Insert one letter to any end of the string. </li><li> Delete one letter from any end of the string. </li><li> Change one letter into any other one. </li></ul><p>Moriarty is very smart and after he chooses some substring <span class=\"tex-span\"><i>t</i></span>, he always makes the minimal number of changes to obtain <span class=\"tex-span\"><i>u</i></span>. </p><p>Help Moriarty choose the best substring <span class=\"tex-span\"><i>t</i></span> from all substrings of the string <span class=\"tex-span\"><i>s</i></span>. The substring <span class=\"tex-span\"><i>t</i></span> should minimize the number of changes Moriarty should make to obtain the string <span class=\"tex-span\"><i>u</i></span> from it.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters. The second line contains a non-empty string <span class=\"tex-span\"><i>u</i></span>, consisting of lowercase Latin letters. The lengths of both strings are in the range from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">2000</span>, inclusive.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the only integer — the minimum number of changes that Dr. Moriarty has to make with the string that you choose.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aaaaa<br />aaa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcabc<br />bcd<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abcdef<br />klmnopq<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>7<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample Moriarty can take any substring of length <span class=\"tex-span\">3</span>, and it will be equal to the required message <span class=\"tex-span\"><i>u</i></span>, so Moriarty won't have to make any changes.</p><p>In the second sample you should take a substring consisting of characters from second to fourth ("<span class=\"tex-font-style-tt\">bca</span>") or from fifth to sixth ("<span class=\"tex-font-style-tt\">bc</span>"). Then you will only have to make one change: to change or to add the last character.</p><p>In the third sample the initial string <span class=\"tex-span\"><i>s</i></span> doesn't contain any character that the message should contain, so, whatever string you choose, you will have to make at least <span class=\"tex-span\">7</span> changes to obtain the required message.</p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=C]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Suspects"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Suspects</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating a crime, he identified <span class=\"tex-span\"><i>n</i></span> suspects. He knows for sure that exactly one of them committed the crime. To find out which one did it, the detective lines up the suspects and numbered them from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. After that, he asked each one: \"Which one committed the crime?\". Suspect number <span class=\"tex-span\"><i>i</i></span> answered either \"The crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\", or \"Suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime\". Also, the suspect could say so about himself (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> = <i>i</i></span>).</p><p>Sherlock Holmes understood for sure that exactly <span class=\"tex-span\"><i>m</i></span> answers were the truth and all other answers were a lie. Now help him understand this: which suspect lied and which one told the truth?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ <i>n</i></span>) — the total number of suspects and the number of suspects who told the truth. Next <span class=\"tex-span\"><i>n</i></span> lines contain the suspects' answers. The <span class=\"tex-span\"><i>i</i></span>-th line contains either \"+<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, or \"-<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer, <span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>).</p><p>It is guaranteed that at least one suspect exists, such that if he committed the crime, then exactly <span class=\"tex-span\"><i>m</i></span> people told the truth.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>n</i></span> lines. Line number <span class=\"tex-span\"><i>i</i></span> should contain \"<span class=\"tex-font-style-tt\">Truth</span>\" if suspect number <span class=\"tex-span\"><i>i</i></span> has told the truth for sure. Print \"<span class=\"tex-font-style-tt\">Lie</span>\" if the suspect number <span class=\"tex-span\"><i>i</i></span> lied for sure and print \"<span class=\"tex-font-style-tt\">Not defined</span>\" if he could lie and could tell the truth, too, depending on who committed the crime.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1<br/>+1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Truth<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br/>-1<br/>-2<br/>-3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Not defined<br/>Not defined<br/>Not defined<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br/>+2<br/>-3<br/>+4<br/>-1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Lie<br/>Not defined<br/>Lie<br/>Not defined<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample has the single person and he confesses to the crime, and Sherlock Holmes knows that one person is telling the truth. That means that this person is telling the truth.</p><p>In the second sample there are three suspects and each one denies his guilt. Sherlock Holmes knows that only two of them are telling the truth. Any one of them can be the criminal, so we don't know for any of them, whether this person is telling the truth or not.</p><p>In the third sample the second and the fourth suspect defend the first and the third one. But only one is telling the truth, thus, the first or the third one is the criminal. Both of them can be criminals, so the second and the fourth one can either be lying or telling the truth. The first and the third one are lying for sure as they are blaming the second and the fourth one.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"cd42913023e2a7fcfa8e74f08294509b\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"6e2aa082339bb3ec1a1fdae893dc4a0b46db4272\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_f42d8e7a109b3cdf92f8886e7860f6a998340492\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Suspects</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>As Sherlock Holmes was investigating a crime, he identified <span class=\"tex-span\"><i>n</i></span> suspects. He knows for sure that exactly one of them committed the crime. To find out which one did it, the detective lines up the suspects and numbered them from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i></span>. After that, he asked each one: "Which one committed the crime?". Suspect number <span class=\"tex-span\"><i>i</i></span> answered either "The crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>", or "Suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime". Also, the suspect could say so about himself (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> = <i>i</i></span>).</p><p>Sherlock Holmes understood for sure that exactly <span class=\"tex-span\"><i>m</i></span> answers were the truth and all other answers were a lie. Now help him understand this: which suspect lied and which one told the truth?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup>, 0 ≤ <i>m</i> ≤ <i>n</i></span>) — the total number of suspects and the number of suspects who told the truth. Next <span class=\"tex-span\"><i>n</i></span> lines contain the suspects' answers. The <span class=\"tex-span\"><i>i</i></span>-th line contains either "+<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the crime was committed by suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>, or "-<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), if the suspect number <span class=\"tex-span\"><i>i</i></span> says that the suspect number <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> didn't commit the crime (<span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer, <span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ <i>n</i></span>).</p><p>It is guaranteed that at least one suspect exists, such that if he committed the crime, then exactly <span class=\"tex-span\"><i>m</i></span> people told the truth.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print <span class=\"tex-span\"><i>n</i></span> lines. Line number <span class=\"tex-span\"><i>i</i></span> should contain "<span class=\"tex-font-style-tt\">Truth</span>" if suspect number <span class=\"tex-span\"><i>i</i></span> has told the truth for sure. Print "<span class=\"tex-font-style-tt\">Lie</span>" if the suspect number <span class=\"tex-span\"><i>i</i></span> lied for sure and print "<span class=\"tex-font-style-tt\">Not defined</span>" if he could lie and could tell the truth, too, depending on who committed the crime.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1 1<br />+1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Truth<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br />-1<br />-2<br />-3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Not defined<br />Not defined<br />Not defined<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br />+2<br />-3<br />+4<br />-1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>Lie<br />Not defined<br />Lie<br />Not defined<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>The first sample has the single person and he confesses to the crime, and Sherlock Holmes knows that one person is telling the truth. That means that this person is telling the truth.</p><p>In the second sample there are three suspects and each one denies his guilt. Sherlock Holmes knows that only two of them are telling the truth. Any one of them can be the criminal, so we don't know for any of them, whether this person is telling the truth or not.</p><p>In the third sample the second and the fourth suspect defend the first and the third one. But only one is telling the truth, thus, the first or the third one is the criminal. Both of them can be criminals, so the second and the fourth one can either be lying or telling the truth. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Cipher"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Cipher</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out to be encrypted. The detective tried really hard to decipher the correspondence, but he couldn't understand anything. </p><p>At last, after some thought, he thought of something. Let's say there is a word <span class=\"tex-span\"><i>s</i></span>, consisting of <span class=\"tex-span\">|<i>s</i>|</span> lowercase Latin letters. Then for one <span class=\"tex-font-style-underline\">operation</span> you can choose a certain position <span class=\"tex-span\"><i>p</i></span> (<span class=\"tex-span\">1 ≤ <i>p</i> < |<i>s</i>|</span>) and perform one of the following actions: </p><ul> <li> either replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it; </li><li> or replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it. </li></ul><p>Let us note that letter \"<span class=\"tex-font-style-tt\">z</span>\" doesn't have a defined following letter and letter \"<span class=\"tex-font-style-tt\">a</span>\" doesn't have a defined preceding letter. That's why the corresponding changes are not acceptable. If the operation requires performing at least one unacceptable change, then such operation cannot be performed.</p><p>Two words <span class=\"tex-font-style-underline\">coincide in their meaning</span> iff one of them can be transformed into the other one as a result of zero or more operations.</p><p>Sherlock Holmes needs to learn to quickly determine the following for each word: how many words can exist that coincide in their meaning with the given word, but differs from the given word in at least one character? Count this number for him modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The input data contains several tests. The first line contains the only integer <span class=\"tex-span\"><i>t</i></span> (<span class=\"tex-span\">1 ≤ <i>t</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of tests.</p><p>Next <span class=\"tex-span\"><i>t</i></span> lines contain the words, one per line. Each word consists of lowercase Latin letters and has length from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>, inclusive. Lengths of words can differ.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each word you should print the number of different <span class=\"tex-font-style-bf\">other</span> words that coincide with it in their meaning — not from the words listed in the input data, but from all possible words. As the sought number can be very large, print its value modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>ab<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>aaaaaaaaaaa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>ya<br/>klmbfxzb<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>24<br/>320092793<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Some explanations about the <span class=\"tex-font-style-underline\">operation</span>:</p><ul> <li> Note that for each letter, we can clearly define the letter that follows it. Letter \"<span class=\"tex-font-style-tt\">b</span>\" alphabetically follows letter \"<span class=\"tex-font-style-tt\">a</span>\", letter \"<span class=\"tex-font-style-tt\">c</span>\" follows letter \"<span class=\"tex-font-style-tt\">b</span>\", ..., \"<span class=\"tex-font-style-tt\">z</span>\" follows letter \"<span class=\"tex-font-style-tt\">y</span>\". </li><li> Preceding letters are defined in the similar manner: letter \"<span class=\"tex-font-style-tt\">y</span>\" precedes letter \"<span class=\"tex-font-style-tt\">z</span>\", ..., \"<span class=\"tex-font-style-tt\">a</span>\" precedes letter \"<span class=\"tex-font-style-tt\">b</span>\". </li><li> Note that the operation never changes a word's length. </li></ul><p>In the first sample you can obtain the only other word \"<span class=\"tex-font-style-tt\">ba</span>\". In the second sample you cannot obtain any other word, so the correct answer is <span class=\"tex-span\">0</span>.</p><p>Consider the third sample. One operation can transform word \"<span class=\"tex-font-style-tt\">klmbfxzb</span>\" into word \"<span class=\"tex-font-style-tt\">klmcexzb</span>\": we should choose <span class=\"tex-span\"><i>p</i> = 4</span>, and replace the fourth letter with the following one (\"<span class=\"tex-font-style-tt\">b</span>\" <span class=\"tex-span\"> → </span> \"<span class=\"tex-font-style-tt\">c</span>\"), and the fifth one — with the preceding one (\"<span class=\"tex-font-style-tt\">f</span>\" <span class=\"tex-span\"> → </span> \"<span class=\"tex-font-style-tt\">e</span>\"). Also, we can obtain many other words from this one. An operation can transform word \"<span class=\"tex-font-style-tt\">ya</span>\" only into one other word \"<span class=\"tex-font-style-tt\">xb</span>\". </p><p>Word \"<span class=\"tex-font-style-tt\">ya</span>\" coincides in its meaning with words \"<span class=\"tex-font-style-tt\">xb</span>\", \"<span class=\"tex-font-style-tt\">wc</span>\", \"<span class=\"tex-font-style-tt\">vd</span>\", ..., \"<span class=\"tex-font-style-tt\">ay</span>\" (overall there are <span class=\"tex-span\">24</span> other words). The word \"<span class=\"tex-font-style-tt\">klmbfxzb</span> has many more variants — there are <span class=\"tex-span\">3320092814</span> other words that coincide with in the meaning. So the answer for the first word equals <span class=\"tex-span\">24</span> and for the second one equals <span class=\"tex-span\">320092793</span> — the number <span class=\"tex-span\">3320092814</span> modulo <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span></p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"38600b323806d94a4aec2bc43858c7ba\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"6e2aa082339bb3ec1a1fdae893dc4a0b46db4272\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"E\" data-uuid=\"ps_d0f83b3701baf37ade5c9579995cc33a40dbd856\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Cipher</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out to be encrypted. The detective tried really hard to decipher the correspondence, but he couldn't understand anything. </p><p>At last, after some thought, he thought of something. Let's say there is a word <span class=\"tex-span\"><i>s</i></span>, consisting of <span class=\"tex-span\">|<i>s</i>|</span> lowercase Latin letters. Then for one <span class=\"tex-font-style-underline\">operation</span> you can choose a certain position <span class=\"tex-span\"><i>p</i></span> (<span class=\"tex-span\">1 ≤ <i>p</i> < |<i>s</i>|</span>) and perform one of the following actions: </p><ul> <li> either replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it; </li><li> or replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i></sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">precedes</span> it and replace letter <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>p</i> + 1</sub></span> with the one that alphabetically <span class=\"tex-font-style-bf\">follows</span> it. </li></ul><p>Let us note that letter "<span class=\"tex-font-style-tt\">z</span>" doesn't have a defined following letter and letter "<span class=\"tex-font-style-tt\">a</span>" doesn't have a defined preceding letter. That's why the corresponding changes are not acceptable. If the operation requires performing at least one unacceptable change, then such operation cannot be performed.</p><p>Two words <span class=\"tex-font-style-underline\">coincide in their meaning</span> iff one of them can be transformed into the other one as a result of zero or more operations.</p><p>Sherlock Holmes needs to learn to quickly determine the following for each word: how many words can exist that coincide in their meaning with the given word, but differs from the given word in at least one character? Count this number for him modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The input data contains several tests. The first line contains the only integer <span class=\"tex-span\"><i>t</i></span> (<span class=\"tex-span\">1 ≤ <i>t</i> ≤ 10<sup class=\"upper-index\">4</sup></span>) — the number of tests.</p><p>Next <span class=\"tex-span\"><i>t</i></span> lines contain the words, one per line. Each word consists of lowercase Latin letters and has length from <span class=\"tex-span\">1</span> to <span class=\"tex-span\">100</span>, inclusive. Lengths of words can differ.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each word you should print the number of different <span class=\"tex-font-style-bf\">other</span> words that coincide with it in their meaning — not from the words listed in the input data, but from all possible words. As the sought number can be very large, print its value modulo <span class=\"tex-span\">1000000007</span> <span class=\"tex-span\">(10<sup class=\"upper-index\">9</sup> + 7)</span>.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />ab<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />aaaaaaaaaaa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />ya<br />klmbfxzb<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>24<br />320092793<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Some explanations about the <span class=\"tex-font-style-underline\">operation</span>:</p><ul> <li> Note that for each letter, we can clearly define the letter that follows it. Letter "<span class=\"tex-font-style-tt\">b</span>" alphabetically follows letter "<span class=\"tex-font-style-tt\">a</span>", letter "<span class=\"tex-font-style-tt\">c</span>" follows letter "<span class=\"tex-font-style-tt\">b</span>", ..., "<span class=\"tex-font-style-tt\">z</span>" follows letter "<span class=\"tex-font-style-tt\">y</span>". </li><li> Preceding letters are defined in the similar manner: letter "<span class=\"tex-font-style-tt\">y</span>" precedes letter "<span class=\"tex-font-style-tt\">z</span>", ..., "<span class=\"tex-font-style-tt\">a</span>" precedes letter "<span class=\"tex-font-style-tt\">b</span>". </li><li> Note that the operation never changes a word's length. </li></ul><p>In the first sample you can obtain the only other word "<span class=\"tex-font-style-tt\">ba</span>". In the second sample you cannot obtain any other word, so the correct answer is <span class=\"tex-span\">0</span>.</p><p>Consider the third sample. One operation can transform word "<span class=\"tex-font-style-tt\">klmbfxzb</span>" into word "<span class=\"tex-font-style-tt\">klmcexzb</span>": we should choose <span class=\"tex-span\"><i>p</i> = 4</span>, and replace the fourth letter with the following one ("<span class=\"tex-font-style-tt\">b</span>" <span class=\"tex-span\"> → </span> "<span class=\"tex-font-style-tt\">c</span>"), and the fifth one — with the preceding one ("<span class=\"tex-font-style-tt\">f</span>" <span class=\"tex-span\"> → </span> "<span class=\"tex-font-style-tt\">e</span>"). Also, we can obtain many other words from this one. An operation can transform word "<span class=\"tex-font-style-tt\">ya</span>" only into one other word "<span class=\"tex-font-style-tt\">xb</span>". </p><p>Word "<span class=\"tex-font-style-tt\">ya</span>" coincides in its meaning with words "<span class=\"tex-font-style-tt\">xb</span>", "<span class=\"tex-font-style-tt\">wc</span>", "<span class=\"tex-font-style-tt\">vd</span>", ..., "<span class=\"tex-font-style-tt\">ay</span>" (overall there are <span class=\"tex-span\">24</span> other words). The word "<span class=\"tex-font-style-tt\">klmbfxzb</span> has many more variants — there are <span class=\"tex-span\">3320092814</span> other words that coincide with in the meaning. So the answer for the first word equals <span class=\"tex-span\">24</span> and for the second one equals <span class=\"tex-span\">320092793</span> — the number <span class=\"tex-span\">3320092814</span> modulo <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span></p></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=E]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = Codeforces.getFromStorage(uuid);\r\n if (previousStatementText) {\r\n if (previousStatementText !== statementText) {\r\n $problem.find(\".diff-notifier\").show();\r\n\r\n $problem.find(\".diff-notifier-close\").click(function() {\r\n Codeforces.putToStorageTtl(uuid, statementText, 6 * 60 * 60);\r\n $problem.find(\".diff-notifier\").hide();\r\n });\r\n\r\n 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:15</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='3ad8d1e85d83b9889307a2bf58bcdd9b'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> 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class=\"rated-user user-orange\">Sammarize</a>,\r\n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/ru.png\" alt=\"In Russian\" title=\"In Russian\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><h2>A (Div2) Результат игры</h2><p>В этой игре можно было просто сделать, то, что просят в условии.А именно, завести счётчик, перебрать все клетки поля, и для каждой клетки найти сумму чисел в клетках, стоящих с ней на одной горизонтали, сумму чисел в клетках, стоящих с ней на одной вертикали, и сравнить эти суммы. Если сумма по вертикали больше, увеличить счётчик на один. После того, как перебраны все клетки, вывести счётчик. Максимальная сумма может быть <span class=\"tex-span\">2 × 30 × 100 = 6 000</span>, поэтому для её достаточно типа <em>int</em>.</p><h2>B (Div2) След</h2><p>Извиняюсь за кривой </p><p>Давайте для начала отсортируем радиусы окружностей по убыванию. Пусть у нас теперь радиус первой окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub></span>, второй окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">2</sub></span>, ..., последней окружности — <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>, где <span class=\"tex-span\"><i>r</i><sub class=\"lower-index\">1</sub> > <i>r</i><sub class=\"lower-index\">2</sub> > ... > <i>r</i><sub class=\"lower-index\"><i>n</i></sub></span>. Внешняя область — так, которая снаружи первой окружности — покрашена в синий цвет, значит, область между первой и второй окружностью покрашена в красный. Далее, область между второй и третьей окружностью покрашена в синий цвет, между третьей и четвёртой — в красный, между четвёртой и пятой — в синий, и так далее.</p><p>Первая область, закрашенная в красный цвет (область между первой и второй окружностями) — это вся область внутри первой окружности, из которой выкинули внутреннюю область второй окружности. Значит, площадь это области равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup>)</span>. Аналогично, площадь второй красной области (между третьей и четвёртой окружностями) равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup>)</span>. И так далее. Значит, суммарная их площадь равна <span class=\"tex-span\">π × (<i>r</i><sub class=\"lower-index\">1</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">2</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">3</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">4</sub><sup class=\"upper-index\">2</sup> + <i>r</i><sub class=\"lower-index\">5</sub><sup class=\"upper-index\">2</sup> - <i>r</i><sub class=\"lower-index\">6</sub><sup class=\"upper-index\">2</sup> + ...)</span>. Значит, чтобы посчитать ответ можно, например, сложить квадраты радиусов окружностей с нечётным номером, вычесть из полученной суммы квадраты радиусов всех окружностей с чётными номерами, и полученную величину умножить на \\pi.</p><p>Может возникнуть небольшое затруднение с последней окружностью. Если число окружностей нечётно, то последняя область — не кольцо между двумя окружностями, а круг. Но это, на самом деле, ничего не меняет: тогда последняя окружность имеет нечётный номер, и квадрат её радиуса надо тоже прибавить к сумме.</p><h2>A (Div1) — C (Div2) Сообщение</h2><p>Для начала, добавим к строке <span class=\"tex-span\"><i>s</i></span> с обоих концов по 2000 фиктивному символу — например, <<#>>. Заметим, что это не повлияло на ответ. Действительно, пусть мы взяли подстроку <span class=\"tex-span\"><i>t</i></span>, частично или полностью состоящую из <<#>>. Тогда все символы <<#>> надо было бы заменить. Но если бы их просто не было, то нужные символы надо было бы добавить.</p><p>Рассмотрим оптимальную подстроку <span class=\"tex-span\"><i>t</i></span>, и последовательность действий, которую надо с ней сделать, чтобы превратить её в строку <span class=\"tex-span\"><i>u</i></span>. Рассмотрим первое добавление или удаление символа с одного из концов.</p><p>Заметим, что это не удаление. Ведь если мы выбрали подстроку <span class=\"tex-span\"><i>t</i></span> и удалили из неё, к примеру, последний символ, то его не надо было бы и брать, потому что для строки <span class=\"tex-span\"><i>t</i></span> без последнего символа надо на одно действие меньше, чем для всей строки <span class=\"tex-span\"><i>t</i></span>.</p><p>А теперь заметим, что это и не добавление. Действительно, пусть мы рассмотрели строку <span class=\"tex-span\"><i>t</i></span>, некоторое время меняли в ней символы на другие, и наконец, добавили один, скажем, в начале. Тогда - Если слева от строки есть символ (то есть, строка там ещё не кончается), то можно было его взять сразу (то есть, рассмотреть не <span class=\"tex-span\"><i>t</i></span>, а <span class=\"tex-span\"><i>t</i></span> с ещё одним символом слева). Вместо того, чтобы добавлять символ, можно заменить существующий — это тоже занимает одной действие. - Если слева от строки нету символа (то есть, первый символ <span class=\"tex-span\"><i>t</i></span> является первым символом строки <span class=\"tex-span\"><i>s</i></span>), тогда в <span class=\"tex-span\"><i>t</i></span> есть как минимум 2000 <<#>>. Значит, либо ответ для такой строки как минимум 2000, потому что каждую решётку надо удалить или заменить; либо никаких символов, кроме решёток, в строке <span class=\"tex-span\"><i>t</i></span> нет, и тогда надо сделать как минимум <span class=\"tex-span\">|<i>u</i>|</span> действий, потому что каждый символ <span class=\"tex-span\"><i>u</i></span> надо добавить (или сделать из другого символа). Но чтобы получить всего <span class=\"tex-span\">|<i>u</i>|</span> действий, достаточно взять любую подстроку длины <span class=\"tex-span\">|<i>u</i>|</span>.</p><p>Таким образом, существует оптимальная подстрока <span class=\"tex-span\"><i>t</i></span>, из которой получается <span class=\"tex-span\"><i>u</i></span> без добавлений и удалений. Это ключевой момент решения! Ведь это означает, что длина такой строки равна длине <span class=\"tex-span\"><i>u</i></span>. Значит, достаточно перебрать подстроки строки <span class=\"tex-span\"><i>s</i></span> длины <span class=\"tex-span\">|<i>u</i>|</span>. Всего таких подстрок <span class=\"tex-span\"><i>O</i>(|<i>s</i>|)</span>, и для каждой подстроки легко за время <span class=\"tex-span\"><i>O</i>(|<i>u</i>|)</span> посчитать необходимое количество изменений — это просто количество символов, которые надо заменить.</p><p>Таким образом, получается очень простое в написании решение за время <span class=\"tex-span\"><i>O</i>(|<i>s</i>| × |<i>u</i>|)</span>.</p><h2>B (Div1) — D (Div2) Подозреваемые</h2><p>Будем называть людей, которые сказали <<Убийство совершил подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span>>> <em>обвиняющими</em>, а людей, которые сказали <<Подозреваемый номер <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> не совершал убийства>> — <em>оправдывающими</em>. Рассмотрим подозреваемого номер <span class=\"tex-span\"><i>k</i></span>. Предположим, что он совершил убийство и посчитаем, сколько тогда человек сказали правду. Люди, которые сказали правду — это люди, которые обвиняли <em>его</em>, и люди, которые оправдывали <em>не его</em>. Таким образом, их количество — это количество людей, которые обвинили его, плюс количество людей, которые оправдали <em>кого-либо</em>, и минус количество людей, которые оправдали <em>его</em>. Таким образом, нам надо знать - количество людей, которые кого-либо обвиняют (это легко посчитать за <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span>) - для каждого подозреваемого количество людей которые его обвиняют - для каждого подозреваемого количество людей которые его оправдывают Последние две величины легко посчитать за время <span class=\"tex-span\"><i>O</i>(<i>n</i>)</span> для всех подозреваемых. Действительно, пусть <span class=\"tex-span\"><i>i</i></span>-того человека обвиняют <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> людей и оправдывают <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> людей. Тогда надо просто для каждого человека номер <span class=\"tex-span\"><i>i</i></span>, если он оправдывающий, то увеличить <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>, а если обвиняет — увеличить <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></sub></span>.</p><p>После этих действий можно за <span class=\"tex-span\"><i>O</i>(1)</span> посчитать для каждого подозреваемого число людей, которые говорят правду в том случае, если он преступник, и если это количество равно <span class=\"tex-span\"><i>m</i></span>, то данный человек может быть преступником. А после того, как мы нашли список возможных преступников, то не составляет труда для каждого человека определить, может ли он говорить правду и может ли он врать.</p><h2>С (Div1) — E (Div2) Шифр</h2><p>Давайте в словах записывать вместо букв цифры: вместо <<a>> — <span class=\"tex-span\">0</span>, вместо <<b>> — <span class=\"tex-span\">1</span>, и так далее. Тогда разрешенные операции такие: рассмотреть два соседних числа, и одно из них увеличить на один, а другое — уменьшить на один. Для начала докажем ключевое утверждение задачи: <em>два слова имеют одинаковый смысл тогда и только тогда, когда у них одинаковая длина и одинакова сумма букв</em>.</b></a></p><p>Я мог бы привести полное и строгое доказательство этого факта, но оно будет длинным и немного занудным и, думается мне, его вряд ли кто-нибудь будет читать. Лучше я просто опишу две переформулировки задачи, в которых этого утверждение становится более очевидным.</p><p><strong>1.</strong> Переформулировка первая. Представим себе, что у нас вместо каждого числа — стопка монет, от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> штук. Тогда разрешенные действия — это переложить одну монету из какой-то стопки в соседнюю так, чтобы во всех стопках оставалось от <span class=\"tex-span\">0</span> до <span class=\"tex-span\">25</span> монет.</p><p><strong>2.</strong> Переформулировка вторая. Рассмотрим последовательность <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\"><i>i</i> = 0, ..., <i>n</i></span>), такую, что <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> равно сумме первых <span class=\"tex-span\"><i>i</i></span> чисел в слове. Последовательность неубывает и разность между соседними элементами последовательности не превосходит <span class=\"tex-span\">25</span>. Тогда разрешенная операция — это изменить одно из чисел на один в любую сторону, так, чтобы разность между любыми двумя соседними числами по-прежнему не превосходила <span class=\"tex-span\">25</span>, и последовательность по-прежнему неубывала.</p><p>Таким образом, нам надо посчитать, сколько слов такой же длинны имеют такую же сумму букв. Это легко сделать сразу для всех слов длины не больше <span class=\"tex-span\">100</span>. Посчитаем с помощью динамики такую величину <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>]</span> : количество слов длины <span class=\"tex-span\"><i>l</i></span> с суммой букв <span class=\"tex-span\"><i>s</i></span>. - База динамики: <span class=\"tex-span\"><i>l</i> = 0</span>. Есть ровно одно слово (пустое, оно же единственное слово длины <span class=\"tex-span\">0</span>) с суммой букв <span class=\"tex-span\">0</span>, и по <span class=\"tex-span\">0</span> слов с любой другой суммой букв. - Переход динамики: очень простой. Чтобы узнать, сколько слов длины <span class=\"tex-span\"><i>l</i></span> имеют сумму <span class=\"tex-span\"><i>s</i></span>, надо перебрать, какая может быть последняя буква у этого слова: <span class=\"tex-span\"><i>x</i>[<i>l</i>][<i>s</i>] = <i>x</i>[<i>l</i> - 1][<i>s</i>] + <i>x</i>[<i>l</i> - 1][<i>s</i> - 1] + ... + <i>x</i>[<i>l</i> - 1][<i>s</i> - 25]</span>. Конечно, надо не забыть считать эту величину по модулю <span class=\"tex-span\">10<sup class=\"upper-index\">9</sup> + 7</span>.</p><p>После того, как мы посчитали эту величину для всех <span class=\"tex-span\">0 ≤ <i>l</i> ≤ 100, 0 ≤ <i>s</i> ≤ 2500</span> за <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25)</span> памяти и <span class=\"tex-span\"><i>O</i>(100<sup class=\"upper-index\">2</sup> × 25<sup class=\"upper-index\">2</sup>)</span> времени, надо просто для каждого слова найти его длину сумму букв и вывести ответ (не забыв вычесть <span class=\"tex-span\">1</span>).</p><h2>D (Div1) Улики</h2><h3>Как придумать формулу</h3><p>Простите все, кому это непривычно, но поскольку интерпретатор ТеХа на Codeforces в данный момент несколько кривоват, вместо традиционных нижних индексов будут нетрадиционные верхние. Это не степени, о степенях я буду оповещать отдельно.</p><p>Говоря математическим языком, в задаче надо посчитать количество способов дополнить граф до связного минимальным количеством ребер. Понятно, что сам граф не имеет значения — важны только компоненты связности. Более того, сами компоненты связности не важны, важны только их размеры.</p><p>Итак, пусть у нас есть <span class=\"tex-span\"><i>k</i></span> компонент связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, ..., <i>s</i><sup class=\"upper-index\"><i>k</i></sup></span>.Посмотрим, чем равна искомая величина для маленьких <span class=\"tex-span\"><i>k</i></span>.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 1</span>. Тогда граф уже связный, есть <span class=\"tex-span\">1</span> способ добавить ноль ребер.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 2</span>. Тогда в графе две компоненты связности и надо добавить одно ребро между ними. Существует <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup></span> способ выбрать вершину из первой компоненты, <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">2</sup></span> способов — из второй, всего <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup></span> способов.</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 3</span>. Тогда в графе три компоненты связности, и надо провести два ребра, которые будут соединять различные пары компонент связности. Общее количество способов будет равно <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> + <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × (<i>s</i><sup class=\"upper-index\">1</sup> + <i>s</i><sup class=\"upper-index\">2</sup> + <i>s</i><sup class=\"upper-index\">3</sup>) = <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> × <i>n</i></span>.</p><p>Участники с самой богатой фантазией могли уже сейчас догадаться до правильной формулы. Но лучше посмотрим на следующее значение <span class=\"tex-span\"><i>k</i></span>:</p><p>Пусть <span class=\"tex-span\"><i>k</i> = 4</span>. Тогда в графе <span class=\"tex-span\">4</span> компоненты связности размера <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\">1</sup>, <i>s</i><sup class=\"upper-index\">2</sup>, <i>s</i><sup class=\"upper-index\">3</sup>, <i>s</i><sup class=\"upper-index\">4</sup></span>. Надо провести три ребра. Немного подумав, можно понять, что эти рёбра либо будут соединять одну из компонент связности с остальными тремя, либо первую со второй, вторую — с третьей, а третью — с четвёртой (разумеется, компоненты могут следовать в любом порядке). </p><p>Количество способов первого типа: <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">4</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup> = ((<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">3</sup>)<sup class=\"upper-index\">2</sup> + (<i>s</i><sup class=\"upper-index\">4</sup>)<sup class=\"upper-index\">2</sup>) × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>.</p><p>Количество способов второго типа: есть две компоненты связности, из которых выходит по два ребра. Пусть это первая и вторая. Тогда одно ребро проведено между ними, и ещё одно — из них в другие компоненты связности. Эти два ребра могут быть проведены двумя способами: от первой к третьей, а от второй к четвёртой, или наоборот. Значит, количество таких способов равно <span class=\"tex-span\">2 × (<i>s</i><sup class=\"upper-index\">1</sup>)<sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">2</sup>)<sup class=\"upper-index\">2</sup> × <i>s</i><sup class=\"upper-index\">3</sup> × <i>s</i><sup class=\"upper-index\">4</sup> = 2<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup> × (<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span>. И Таких слагаемых <span class=\"tex-span\">6</span> штук. Просуммировав их всех и прибавив к ним способы первого типа, можно вынести множитель <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>)</span> за скобки, и останется аккурат формула квадрата суммы 4-х слагаемых. Значит, общее количество способов будет равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup><i>s</i><sup class=\"upper-index\">3</sup><i>s</i><sup class=\"upper-index\">4</sup>) × <i>n</i><sup class=\"upper-index\">2</sup></span>.</p><p>На этом месте можно было уже легко догадаться до формулы <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>, тем более, что в первом случае получается как раз <span class=\"tex-span\">1 = (<i>s</i><sup class=\"upper-index\">1</sup>) × <i>n</i><sup class=\"upper-index\"> - 1</sup></span>.</p><h3>Как доказать формулу</h3><p>Осталось только эту формулу доказать (хотя, конечно, для того, чтобы сдать задачу, доказательства не требовалось =))</p><p>Итак, пусть есть некий набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра, который дополняет граф до связного. Построим по нему <strong>две последовательности чисел</strong>: (x^1, x^2, ..., x^{k-2}) и (a^1,a^2,...,a^k). При это каждое <span class=\"tex-span\"><i>x</i></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>n</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> может быть любым числом от 1 до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>. Легко понять что таких <strong>пар последовательностей</strong> аккурат столько же, сколько (якобы!) способов дополнить наш граф до связного.</p><p>Пара последовательностей же строится следующим образом.</p><p>Для начала заметим, что этот набор из <span class=\"tex-span\"><i>k</i> - 1</span> ребра как бы образует дерево, в вершинах которого — компоненты связности.</p> <ol> <li><p>Рассмотрим минимальную по номеру компоненту связности, из которой выходит только одно дополняющее ребро. Пусть это компонента номер <span class=\"tex-span\"><i>i</i></span> и ребро соединяет вершину номер <span class=\"tex-span\"><i>t</i></span> в компоненте номер <span class=\"tex-span\"><i>i</i></span> и вершину номер <span class=\"tex-span\"><i>b</i></span> в другой компоненте. Тогда <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup> = <i>b</i></span>, а <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> равно (внимание!) номеру вершины <span class=\"tex-span\"><i>t</i></span> среди вершин компоненты <span class=\"tex-span\"><i>i</i></span>, то есть, числу от <span class=\"tex-span\">1</span> до <span class=\"tex-span\"><i>s</i><sup class=\"upper-index\"><i>i</i></sup></span>.</p></li> <li><p>Одна из компонент связности теперь отвалилась от графа. Остальные <span class=\"tex-span\"><i>k</i> - 2</span> ребер дополняют оставшиеся <span class=\"tex-span\"><i>k</i> - 2</span> компоненты до связного графа. Повторим ту же процедуру еще <span class=\"tex-span\"><i>k</i> - 1</span> раз.</p></li> <li><p>Осталось одно ребро. Оно соединяет две компоненты связности <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span>, которые ещё не упомянуты во второй последовательности. Первая же последовательность заполнена — в ней как раз <span class=\"tex-span\"><i>k</i> - 2</span> элемента. Осталось во вторую последовательность на места номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> записать номера концов оставшегося ребра среди вершин компонент номер <span class=\"tex-span\"><i>u</i></span> и <span class=\"tex-span\"><i>v</i></span> соответственно.</p></li> </ol><p>Итого, для каждого способа дополнить граф до связного существует такая пара последовательностей. Заметим, что если компонента <span class=\"tex-span\"><i>i</i></span> была <<висячей>>, то есть, соединялась только с одной другой компонентой, то её вершины не упоминаются в первой последовательности. А если не была висячей — то упоминаются, потому что все рёбра, которые выходят из этой компоненты, надо выкинуть. Каждое ребро, которое мы выкидываем, упирается одним концов в висячую компоненту. И когда было выкинуто первое ребро, выходящее из компоненты <span class=\"tex-span\"><i>i</i></span>, компонента <span class=\"tex-span\"><i>i</i></span> не была висячей. Значит, при выкидывании этого ребра в первую последовательность была записана вершина из компоненты <span class=\"tex-span\"><i>i</i></span>.</p><p>Более того, как следует из рассуждений выше, в любой момент в процессе записи первой последовательности, если выясняется, что в ней больше не будет упомянуты вершины из компоненты <span class=\"tex-span\"><i>i</i></span>, то это означает, что компонента <span class=\"tex-span\"><i>i</i></span> либо уже выкинута, либо в данный момент висячая.</p><p>Значит, в начальный момент, и каждый момент в процессе построения первой последовательности, по оставшемуся куску последовательности можно судить, какие вершины в данный момент висячие.</p><p>Итак, пусть у нас есть какой-то, неизвестный способ дополнить граф до связного и мы построили по нему две последовательности <span class=\"tex-span\">(<i>x</i><sup class=\"upper-index\">1</sup>, <i>x</i><sup class=\"upper-index\">2</sup>, ..., <i>x</i><sup class=\"upper-index\"><i>k</i> - 2</sup>)</span> и <span class=\"tex-span\">(<i>a</i><sup class=\"upper-index\">1</sup>, <i>a</i><sup class=\"upper-index\">2</sup>, ..., <i>a</i><sup class=\"upper-index\"><i>k</i></sup>)</span>. Восстановим по ним дополнение графа до связного.</p> <ol> <li><p>Рассмотрим <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Это число говорит нам, что сначала было выкинуто ребро одним концом в <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>, а другим — в наименьшей по номеру висячей компоненте связности. Мы можем её определить, так как знаем текущий список висячих компонент. Пусть это компонента <span class=\"tex-span\"><i>i</i></span>. Тогда в <span class=\"tex-span\"><i>a</i><sup class=\"upper-index\"><i>i</i></sup></span> записан номер вершины в компоненте <span class=\"tex-span\"><i>i</i></span>, которая соединена с <span class=\"tex-span\"><i>x</i><sup class=\"upper-index\">1</sup></span>. Итак, одно ребро восстановили. Выкидываем компоненту номер <span class=\"tex-span\"><i>i</i></span>.</p></li> <li><p>Делаем эту операцию ещё <span class=\"tex-span\"><i>k</i> - 1</span> раз. Выкинуты <span class=\"tex-span\"><i>k</i> - 2</span> компоненты и восстановлены <span class=\"tex-span\"><i>k</i> - 2</span> ребра. Осталось два неиспользованных элемента второй последовательности, которые определяют вершины в двух оставшихся компонентах. Эти вершины и надо соединить <span class=\"tex-span\"><i>k</i> - 1</span>-ым ребром.</p></li> </ol><p>Итого, по каждой паре последовательностей восстанавливается дополнение до связного графа, из которого эта пара последовательностей была получена. Значит, количество способов дополнить граф до связного равно количеству пар последовательностей, которое и равно <span class=\"tex-span\">(<i>s</i><sup class=\"upper-index\">1</sup><i>s</i><sup class=\"upper-index\">2</sup>... <i>s</i><sup class=\"upper-index\"><i>k</i></sup>) × <i>n</i><sup class=\"upper-index\"><i>k</i> - 2</sup></span>.</p><h2>E (Div1) Оладьи миссис Хадсон</h2><p>Для начала заметим, что легко придумать очень простое решение этой задачи. Можно просто хранить остаток от деления каждой из цен на каждое из 25 простых чисел от 2 до 97. Тогда каждый запрос будет выполняться за <span class=\"tex-span\"><i>O</i>(25 × 10000)</span>. И всего решение будет работать за <span class=\"tex-span\"><i>O</i>(25 × 10000 × 30000) = <i>O</i>(7, 5 × 10<sup class=\"upper-index\">9</sup>)</span> взятий по модулю. К сожалению, это не укладывается в ограничение по времени =)</p><p>Первая идея авторского решения: если результаты наших действий класть с мап и доставать оттуда при необходимости, это сильно ускорит работу программы. Но мапить надо с умом! Во-первых, надо класть в мап остатки от произведения цен баночек, подходящих под шаблон, по модулю простых чисел. Во-вторых, все шаблоны, под которые подходят все номера, надо считать идеинтичными, независимо от основания системы исчисления.</p><p>Нет смысла приводить здесь нудные вычисления, показывающие, что это действительно дает прирост производительности — гораздо проще написать программу, которая это подсчитает. Получается порядка <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup></span> чисел, остатки которых надо перемножить, вместо <span class=\"tex-span\">10 000 × 30 000 = 3 × 10<sup class=\"upper-index\">8</sup></span>.</p><p>Однако всё же <span class=\"tex-span\">3 × 10<sup class=\"upper-index\">7</sup> × 25 = 7, 5 × 10<sup class=\"upper-index\">8</sup></span> взятий по модулю. Понятно, что это всё равно не уложится в 5 секунд.</p><p>Вторая идея авторского решения.</p><p>Рассмотрим 4 модуля:</p><p><span class=\"tex-span\">1224469897 = 7 × 17 × 37 × 47 × 61 × 97</span></p><p><span class=\"tex-span\">1503325967 = 11 × 13 × 41 × 43 × 67 × 89</span></p><p><span class=\"tex-span\">1336143462 = 2 × 3 × 23 × 31 × 53 × 71 × 83</span></p><p><span class=\"tex-span\">937397015 = 5 × 19 × 29 × 59 × 73 × 79</span></p><p>Квадрат всех этих 4 чисел влезает в знаковый 64-битный тип данных и их произведение делится на все простые числа до 100. Для каждой из <span class=\"tex-span\">10 000</span> цен чисел будем хранить остаток этой цены по каждому из четырех модулей. Легко посчитать остаток произведения и прибавить к нему константу. По четырём остаткам легко определить, какой будет минимальный делитель — перебрать 25 вариантов. </p><p>Итого, такая оптимизация дает асимптотику <span class=\"tex-span\"><i>O</i>(4 × (3 × 10<sup class=\"upper-index\">7</sup>)) = <i>O</i>(1, 2 × 10<sup class=\"upper-index\">8</sup>)</span>.</p></div>\r\n\r\n </div>\r\n\r\n\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-485-4019\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"485\",\n blogEntryId: \"4005\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=codeforces\" class=\"tag notice\" style=\"text-decoration: none;\">codeforces</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=round+110\" class=\"tag notice\" style=\"text-decoration: none;\">round 110</a>,\r\n </span>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=%D1%80%D0%B0%D0%B7%D0%B1%D0%BE%D1%80\" class=\"tag notice\" style=\"text-decoration: none;\">разбор</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+25</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4019\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/Sammarize\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/Sammarize\">\n Sammarize\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/02/2012 01:20\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4005#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4005#comments\">\n 3\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4029\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (2)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"604089\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/greedy_me\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/329685/avatar/c4a523e01cd72759.jpg'/> </a>\n <div><a href=\"/profile/greedy_me\" title=\"Candidate Master greedy_me\" class=\"rated-user user-violet\">greedy_me</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/14/2020 16:31\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-604089\" href=\"?#comment-604089\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"604089\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"329685\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-604089\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Div 2 C , Google translate</p><p>For starters, add a dummy character to the string s from both ends, for example, << # >>. Note that this did not affect the answer. Indeed, let us take the substring t partially or completely consisting of << # >>. Then all the characters << # >> would have to be replaced. But if they simply did not exist, then the necessary symbols would have to be added.</p><p>Consider the optimal substring t, and the sequence of actions that must be done with it in order to turn it into a string u. Consider the first addition or removal of a character from one end.</p><p>Note that this is not a deletion. After all, if we selected the substring t and, for example, deleted the last character from it, then we would not have to take it, because for a string t without the last character we need one less action than for the entire string t.</p><p>Now note that this is not an addition. Indeed, let us consider the string t, for some time change the characters in it to others, and finally add one, say, at the beginning. Then — If there is a character to the left of the line (that is, the line does not end there), then you could take it right away (that is, consider not t, but t with one more character to the left). Instead of adding a character, you can replace the existing one — this also takes one action. — If there is no character to the left of the line (that is, the first character t is the first character of the string s), then there is at least 2000 << # >> in t. So either the answer for such a row is at least 2000, because each lattice must be removed or replaced; or there are no symbols except grids in line t, and then at least | u | actions, because each u character must be added (or made from another character). But to get everything | u | action, it is enough to take any substring of length | u |.</p><p>Thus, there exists an optimal substring t from which u is obtained without additions or deletions. This is the key to the decision! After all, this means that the length of such a string is equal to the length u. Therefore, it suffices to iterate over the substrings of the string s of length | u |. The total number of such substrings is O (| s |), and for each substring it is easy to calculate the required number of changes during O (| u |) time — this is just the number of characters that need to be replaced.</p><p>Thus, it turns out to be a very easy-to-write solution in time O (| s | × | u |).</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-604089 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-604089 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-604089\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1004916\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/mahdi.hasnat\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/663363/avatar/3da7dd3774c20119.jpg'/> </a>\n <div><a href=\"/profile/mahdi.hasnat\" title=\"Master mahdi.hasnat\" class=\"rated-user user-orange\">mahdi.hasnat</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Feb/14/2023 17:42\">8 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1004916\" href=\"?#comment-1004916\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1004916\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"663363\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1004916\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p><a href=\"https://codeforces.com/problemset/problem/156/D\">D. Clues</a> can be solved from idea of prufer sequence. More about this on <a href=\"https://cp-algorithms.com/graph/pruefer_code.html#number-of-ways-to-make-a-graph-connected\">Cp-algorithm</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1004916 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1004916 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1004916\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4029\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In English</span>\r\n <input 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Next Round"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Next Round</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>\"Contestant who earns a score equal to or greater than the <span class=\"tex-span\"><i>k</i></span>-th place finisher's score will advance to the next round, as long as the contestant earns a positive score...\" — an excerpt from contest rules.</p><p>A total of <span class=\"tex-span\"><i>n</i></span> participants took part in the contest (<span class=\"tex-span\"><i>n</i> ≥ <i>k</i></span>), and you already know their scores. Calculate how many participants will advance to the next round.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>n</i> ≤ 50</span>) separated by a single space.</p><p>The second line contains <span class=\"tex-span\"><i>n</i></span> space-separated integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub>, <i>a</i><sub class=\"lower-index\">2</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>), where <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is the score earned by the participant who got the <span class=\"tex-span\"><i>i</i></span>-th place. The given sequence is non-increasing (that is, for all <span class=\"tex-span\"><i>i</i></span> from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i> - 1</span> the following condition is fulfilled: <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≥ <i>a</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Output the number of participants who advance to the next round.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>8 5<br/>10 9 8 7 7 7 5 5<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 2<br/>0 0 0 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first example the participant on the 5th place earned 7 points. As the participant on the 6th place also earned 7 points, there are 6 advancers.</p><p>In the second example nobody got a positive score.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"101cf0eabeb9c9feb6d2ecf318b6da97\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"30b177ed98d3542271214a365c61094000edb069\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/158\">VK Cup 2012 Qualification Round 1</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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Typewriter\", \"DejaVu Sans Mono\", \"Bitstream Vera Sans Mono\", \"Liberation Mono\", \"Nimbus Mono L\", Monaco, \"Courier New\", Courier, monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4012\" title=\"VK Cup 2012 Qualification Round 1\" target=\"_blank\">Announcement</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"626:627\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4089\" title=\"Simple solution to vk cup Qualification Round 1 and 2\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(en)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"628\" resourceName=\"Simple solution to vk cup Qualification Round 1 and 2\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/158\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/158/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/158/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/158/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/158/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/158/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const 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result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_4cb6aaf6d06268a460b147f44a45efa3022052f4\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Next Round</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>"Contestant who earns a score equal to or greater than the <span class=\"tex-span\"><i>k</i></span>-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules.</p><p>A total of <span class=\"tex-span\"><i>n</i></span> participants took part in the contest (<span class=\"tex-span\"><i>n</i> ≥ <i>k</i></span>), and you already know their scores. Calculate how many participants will advance to the next round.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ <i>n</i> ≤ 50</span>) separated by a single space.</p><p>The second line contains <span class=\"tex-span\"><i>n</i></span> space-separated integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub>, <i>a</i><sub class=\"lower-index\">2</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">0 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>), where <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub></span> is the score earned by the participant who got the <span class=\"tex-span\"><i>i</i></span>-th place. The given sequence is non-increasing (that is, for all <span class=\"tex-span\"><i>i</i></span> from <span class=\"tex-span\">1</span> to <span class=\"tex-span\"><i>n</i> - 1</span> the following condition is fulfilled: <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≥ <i>a</i><sub class=\"lower-index\"><i>i</i> + 1</sub></span>).</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Output the number of participants who advance to the next round.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>8 5<br />10 9 8 7 7 7 5 5<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>6<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4 2<br />0 0 0 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first example the participant on the 5th place earned 7 points. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:13</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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<span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":779,"cells":{"problem_id":{"kind":"string","value":"158B"},"contest":{"kind":"string","value":"158"},"problem":{"kind":"string","value":"B"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"B. Taxi"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Taxi</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>After the lessons <span class=\"tex-span\"><i>n</i></span> groups of schoolchildren went outside and decided to visit Polycarpus to celebrate his birthday. We know that the <span class=\"tex-span\"><i>i</i></span>-th group consists of <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> friends (<span class=\"tex-span\">1 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 4</span>), and they want to go to Polycarpus together. They decided to get there by taxi. Each car can carry at most four passengers. What minimum number of cars will the children need if all members of each group should ride in the same taxi (but one taxi can take more than one group)?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of groups of schoolchildren. The second line contains a sequence of integers <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub>, <i>s</i><sub class=\"lower-index\">2</sub>, ..., <i>s</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 4</span>). The integers are separated by a space, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> is the number of children in the <span class=\"tex-span\"><i>i</i></span>-th group.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the minimum number of taxis necessary to drive all children to Polycarpus.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>5<br/>1 2 4 3 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>8<br/>2 3 4 4 2 1 3 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test we can sort the children into four cars like this:</p><ul> <li> the third group (consisting of four children), </li><li> the fourth group (consisting of three children), </li><li> the fifth group (consisting of three children), </li><li> the first and the second group (consisting of one and two children, correspondingly). </li></ul><p>There are other ways to sort the groups into four cars.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"c79026f310fa5c4b06cc0da9b91de7ee\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"30b177ed98d3542271214a365c61094000edb069\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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=== \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_a4d4820681351086f930c9b79bc4e35265e5353d\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Taxi</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>After the lessons <span class=\"tex-span\"><i>n</i></span> groups of schoolchildren went outside and decided to visit Polycarpus to celebrate his birthday. We know that the <span class=\"tex-span\"><i>i</i></span>-th group consists of <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> friends (<span class=\"tex-span\">1 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 4</span>), and they want to go to Polycarpus together. They decided to get there by taxi. Each car can carry at most four passengers. What minimum number of cars will the children need if all members of each group should ride in the same taxi (but one taxi can take more than one group)?</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of groups of schoolchildren. The second line contains a sequence of integers <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub>, <i>s</i><sub class=\"lower-index\">2</sub>, ..., <i>s</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 4</span>). The integers are separated by a space, <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> is the number of children in the <span class=\"tex-span\"><i>i</i></span>-th group.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the single number — the minimum number of taxis necessary to drive all children to Polycarpus.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>5<br />1 2 4 3 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>4<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>8<br />2 3 4 4 2 1 3 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test we can sort the children into four cars like this:</p><ul> 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:13</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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<span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":780,"cells":{"problem_id":{"kind":"string","value":"158C"},"contest":{"kind":"string","value":"158"},"problem":{"kind":"string","value":"C"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"C. Cd and pwd commands"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Cd and pwd commands</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya is writing an operating system shell, and it should have commands for working with directories. To begin with, he decided to go with just two commands: <span class=\"tex-font-style-tt\">cd</span> (change the current directory) and <span class=\"tex-font-style-tt\">pwd</span> (display the current directory).</p><p>Directories in Vasya's operating system form a traditional hierarchical tree structure. There is a single root directory, denoted by the slash character \"<span class=\"tex-font-style-tt\">/</span>\". Every other directory has a name — a non-empty string consisting of lowercase Latin letters. Each directory (except for the root) has a parent directory — the one that contains the given directory. It is denoted as \"<span class=\"tex-font-style-tt\">..</span>\".</p><p>The command <span class=\"tex-font-style-tt\">cd</span> takes a single parameter, which is a path in the file system. The command changes the current directory to the directory specified by the path. The path consists of the names of directories separated by slashes. The name of the directory can be \"<span class=\"tex-font-style-tt\">..</span>\", which means a step up to the parent directory. «<span class=\"tex-font-style-tt\">..</span>» can be used in any place of the path, maybe several times. If the path begins with a slash, it is considered to be an absolute path, that is, the directory changes to the specified one, starting from the root. If the parameter begins with a directory name (or \"<span class=\"tex-font-style-tt\">..</span>\"), it is considered to be a relative path, that is, the directory changes to the specified directory, starting from the current one.</p><p>The command <span class=\"tex-font-style-tt\">pwd</span> should display the absolute path to the current directory. This path must not contain \"<span class=\"tex-font-style-tt\">..</span>\".</p><p>Initially, the current directory is the root. All directories mentioned explicitly or passed indirectly within any command <span class=\"tex-font-style-tt\">cd</span> are considered to exist. It is guaranteed that there is no attempt of transition to the parent directory of the root directory.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input data contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 50</span>) — the number of commands.</p><p>Then follow <span class=\"tex-span\"><i>n</i></span> lines, each contains one command. Each of these lines contains either command <span class=\"tex-font-style-tt\">pwd</span>, or command <span class=\"tex-font-style-tt\">cd</span>, followed by a space-separated non-empty parameter.</p><p>The command parameter <span class=\"tex-font-style-tt\">cd</span> only contains lower case Latin letters, slashes and dots, two slashes cannot go consecutively, dots occur only as the name of a parent pseudo-directory. The command parameter <span class=\"tex-font-style-tt\">cd</span> does not end with a slash, except when it is the only symbol that points to the root directory. The command parameter has a length from 1 to 200 characters, inclusive.</p><p>Directories in the file system can have the same names.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each command <span class=\"tex-font-style-tt\">pwd</span> you should print the full absolute path of the given directory, ending with a slash. It should start with a slash and contain the list of slash-separated directories in the order of being nested from the root to the current folder. It should contain no dots.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>7<br/>pwd<br/>cd /home/vasya<br/>pwd<br/>cd ..<br/>pwd<br/>cd vasya/../petya<br/>pwd<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>/<br/>/home/vasya/<br/>/home/<br/>/home/petya/<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br/>cd /a/b<br/>pwd<br/>cd ../a/b<br/>pwd<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>/a/b/<br/>/a/a/b/<br/></pre></div></div></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"2f8aa9852b868ad46978ff4014a2e3ac\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"30b177ed98d3542271214a365c61094000edb069\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/158\">VK Cup 2012 Qualification Round 1</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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(!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_1bc099f652a958e64f535159d083f605a2b5b8d9\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. Cd and pwd commands</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Vasya is writing an operating system shell, and it should have commands for working with directories. To begin with, he decided to go with just two commands: <span class=\"tex-font-style-tt\">cd</span> (change the current directory) and <span class=\"tex-font-style-tt\">pwd</span> (display the current directory).</p><p>Directories in Vasya's operating system form a traditional hierarchical tree structure. There is a single root directory, denoted by the slash character "<span class=\"tex-font-style-tt\">/</span>". Every other directory has a name — a non-empty string consisting of lowercase Latin letters. Each directory (except for the root) has a parent directory — the one that contains the given directory. It is denoted as "<span class=\"tex-font-style-tt\">..</span>".</p><p>The command <span class=\"tex-font-style-tt\">cd</span> takes a single parameter, which is a path in the file system. The command changes the current directory to the directory specified by the path. The path consists of the names of directories separated by slashes. The name of the directory can be "<span class=\"tex-font-style-tt\">..</span>", which means a step up to the parent directory. «<span class=\"tex-font-style-tt\">..</span>» can be used in any place of the path, maybe several times. If the path begins with a slash, it is considered to be an absolute path, that is, the directory changes to the specified one, starting from the root. If the parameter begins with a directory name (or "<span class=\"tex-font-style-tt\">..</span>"), it is considered to be a relative path, that is, the directory changes to the specified directory, starting from the current one.</p><p>The command <span class=\"tex-font-style-tt\">pwd</span> should display the absolute path to the current directory. This path must not contain "<span class=\"tex-font-style-tt\">..</span>".</p><p>Initially, the current directory is the root. All directories mentioned explicitly or passed indirectly within any command <span class=\"tex-font-style-tt\">cd</span> are considered to exist. It is guaranteed that there is no attempt of transition to the parent directory of the root directory.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input data contains the single integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 50</span>) — the number of commands.</p><p>Then follow <span class=\"tex-span\"><i>n</i></span> lines, each contains one command. Each of these lines contains either command <span class=\"tex-font-style-tt\">pwd</span>, or command <span class=\"tex-font-style-tt\">cd</span>, followed by a space-separated non-empty parameter.</p><p>The command parameter <span class=\"tex-font-style-tt\">cd</span> only contains lower case Latin letters, slashes and dots, two slashes cannot go consecutively, dots occur only as the name of a parent pseudo-directory. The command parameter <span class=\"tex-font-style-tt\">cd</span> does not end with a slash, except when it is the only symbol that points to the root directory. The command parameter has a length from 1 to 200 characters, inclusive.</p><p>Directories in the file system can have the same names.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>For each command <span class=\"tex-font-style-tt\">pwd</span> you should print the full absolute path of the given directory, ending with a slash. It should start with a slash and contain the list of slash-separated directories in the order of being nested from the root to the current folder. It should contain no dots.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>7<br />pwd<br />cd /home/vasya<br />pwd<br />cd ..<br />pwd<br />cd vasya/../petya<br />pwd<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>/<br />/home/vasya/<br />/home/<br />/home/petya/<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>4<br />cd /a/b<br />pwd<br />cd ../a/b<br />pwd<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>/a/b/<br />/a/a/b/<br /></pre></div></div></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=C]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":781,"cells":{"problem_id":{"kind":"string","value":"158D"},"contest":{"kind":"string","value":"158"},"problem":{"kind":"string","value":"D"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"D. Ice Sculptures"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Ice Sculptures</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The Berland University is preparing to celebrate the 256-th anniversary of its founding! A specially appointed Vice Rector for the celebration prepares to decorate the campus. In the center of the campus <span class=\"tex-span\"><i>n</i></span> ice sculptures were erected. The sculptures are arranged in a circle at equal distances from each other, so they form a regular <span class=\"tex-span\"><i>n</i></span>-gon. They are numbered in clockwise order with numbers from 1 to <span class=\"tex-span\"><i>n</i></span>.</p><p>The site of the University has already conducted a voting that estimated each sculpture's characteristic of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> — the degree of the sculpture's attractiveness. The values of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> can be positive, negative or zero.</p><p>When the university rector came to evaluate the work, he said that this might be not the perfect arrangement. He suggested to melt some of the sculptures so that: </p><ul> <li> the remaining sculptures form a regular polygon (the number of vertices should be between 3 and <span class=\"tex-span\"><i>n</i></span>), </li><li> the sum of the <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> values of the remaining sculptures is maximized. </li></ul><p>Help the Vice Rector to analyze the criticism — find the maximum value of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> sum which can be obtained in this way. It is allowed not to melt any sculptures at all. The sculptures can not be moved.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">3 ≤ <i>n</i> ≤ 20000</span>) — the initial number of sculptures. The second line contains a sequence of integers <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">1</sub>, <i>t</i><sub class=\"lower-index\">2</sub>, ..., <i>t</i><sub class=\"lower-index\"><i>n</i></sub></span>, <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> — the degree of the <span class=\"tex-span\"><i>i</i></span>-th sculpture's attractiveness (<span class=\"tex-span\"> - 1000 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>). The numbers on the line are separated by spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the required maximum sum of the sculptures' attractiveness.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>8<br/>1 2 -3 4 -5 5 2 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>14<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6<br/>1 -2 3 -4 5 -6<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6<br/>1 2 3 4 5 6<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>21<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample it is best to leave every second sculpture, that is, leave sculptures with attractivenesses: 2, 4, 5 и 3.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"b5670e3a18f5f4e0baf9e92dd5ee6a44\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"30b177ed98d3542271214a365c61094000edb069\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"D\" data-uuid=\"ps_cf20e012bd44fb4e6825b52da19392b96be0f9b8\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Ice Sculptures</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>The Berland University is preparing to celebrate the 256-th anniversary of its founding! A specially appointed Vice Rector for the celebration prepares to decorate the campus. In the center of the campus <span class=\"tex-span\"><i>n</i></span> ice sculptures were erected. The sculptures are arranged in a circle at equal distances from each other, so they form a regular <span class=\"tex-span\"><i>n</i></span>-gon. They are numbered in clockwise order with numbers from 1 to <span class=\"tex-span\"><i>n</i></span>.</p><p>The site of the University has already conducted a voting that estimated each sculpture's characteristic of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> — the degree of the sculpture's attractiveness. The values of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> can be positive, negative or zero.</p><p>When the university rector came to evaluate the work, he said that this might be not the perfect arrangement. He suggested to melt some of the sculptures so that: </p><ul> <li> the remaining sculptures form a regular polygon (the number of vertices should be between 3 and <span class=\"tex-span\"><i>n</i></span>), </li><li> the sum of the <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> values of the remaining sculptures is maximized. </li></ul><p>Help the Vice Rector to analyze the criticism — find the maximum value of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> sum which can be obtained in this way. It is allowed not to melt any sculptures at all. The sculptures can not be moved.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">3 ≤ <i>n</i> ≤ 20000</span>) — the initial number of sculptures. The second line contains a sequence of integers <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">1</sub>, <i>t</i><sub class=\"lower-index\">2</sub>, ..., <i>t</i><sub class=\"lower-index\"><i>n</i></sub></span>, <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> — the degree of the <span class=\"tex-span\"><i>i</i></span>-th sculpture's attractiveness (<span class=\"tex-span\"> - 1000 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>). The numbers on the line are separated by spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the required maximum sum of the sculptures' attractiveness.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>8<br />1 2 -3 4 -5 5 2 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>14<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6<br />1 -2 3 -4 5 -6<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>6<br />1 2 3 4 5 6<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>21<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample it is best to leave every second sculpture, that is, leave 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:13</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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<span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":782,"cells":{"problem_id":{"kind":"string","value":"158E"},"contest":{"kind":"string","value":"158"},"problem":{"kind":"string","value":"E"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"E. Phone Talks"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Phone Talks</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Cool J has recently become a businessman Mr. Jackson, and he has to make a lot of phone calls now. Today he has <span class=\"tex-span\"><i>n</i></span> calls planned. For each call we know the moment <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> (in seconds since the start of the day) when it is scheduled to start and its duration <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span> (in seconds). All <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> are different. Mr. Jackson is a very important person, so he never dials anybody himself, all calls will be incoming.</p><p>Mr. Jackson isn't Caesar and he can't do several things at once. If somebody calls him while he hasn't finished the previous conversation, Mr. Jackson puts the new call on hold in the queue. In this case immediately after the end of the current call Mr. Jackson takes the earliest incoming call from the queue and starts the conversation. If Mr. Jackson started the call at the second <span class=\"tex-span\"><i>t</i></span>, and the call continues for <span class=\"tex-span\"><i>d</i></span> seconds, then Mr. Jackson is busy at seconds <span class=\"tex-span\"><i>t</i>, <i>t</i> + 1, ..., <i>t</i> + <i>d</i> - 1</span>, and he can start a new call at second <span class=\"tex-span\"><i>t</i> + <i>d</i></span>. Note that if Mr. Jackson is not busy talking when somebody calls, he can't put this call on hold.</p><p>Mr. Jackson isn't Napoleon either, he likes to sleep. So sometimes he allows himself the luxury of ignoring a call, as if it never was scheduled. He can ignore at most <span class=\"tex-span\"><i>k</i></span> calls. Note that a call which comes while he is busy talking can be ignored as well.</p><p>What is the maximum number of seconds Mr. Jackson can sleep today, assuming that he can choose an arbitrary continuous time segment from the current day (that is, with seconds from the 1-st to the 86400-th, inclusive) when he is not busy talking?</p><p>Note that some calls can be continued or postponed to the next day or even later. However, the interval for sleep should be completely within the current day.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains a pair of integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ <i>n</i> ≤ 4000</span>) separated by a space. Following <span class=\"tex-span\"><i>n</i></span> lines contain the description of calls for today. The description of each call is located on the single line and consists of two space-separated integers <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, (<span class=\"tex-span\">1 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub>, <i>d</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 86400</span>). All <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> are distinct, the calls are given in the order of strict increasing <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>Scheduled times of calls [<span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub> + <i>d</i><sub class=\"lower-index\"><i>i</i></sub> - 1</span>] can arbitrarily intersect.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a number from 0 to 86400, inclusive — the maximally possible number of seconds for Mr. Jackson to sleep today.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br/>30000 15000<br/>40000 15000<br/>50000 15000<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>49999<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 1<br/>1 20000<br/>10000 10000<br/>20000 20000<br/>25000 10000<br/>80000 60000<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>39999<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the most convenient way is to ignore the first two calls.</p><p>In the second sample it is best to ignore the third call. In this case Mr. Jackson will have been speaking:</p><ul> <li> first call: from 1-st to 20000-th second, </li><li> second call: from 20001-st to 30000-th second, </li><li> fourth call: from 30001-st to 40000-th second (the third call is ignored), </li><li> fifth call: from 80000-th to 139999-th second. </li></ul><p>Thus, the longest period of free time is from the 40001-th to the 79999-th second.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"50f0c5c7d8ec1a1afb0402c06cb64b7b\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"30b177ed98d3542271214a365c61094000edb069\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"E\" data-uuid=\"ps_6cdacdbd744c7f81fa927bce5b5ef891fbd0ef3e\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Phone Talks</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Cool J has recently become a businessman Mr. Jackson, and he has to make a lot of phone calls now. Today he has <span class=\"tex-span\"><i>n</i></span> calls planned. For each call we know the moment <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> (in seconds since the start of the day) when it is scheduled to start and its duration <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span> (in seconds). All <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> are different. Mr. Jackson is a very important person, so he never dials anybody himself, all calls will be incoming.</p><p>Mr. Jackson isn't Caesar and he can't do several things at once. If somebody calls him while he hasn't finished the previous conversation, Mr. Jackson puts the new call on hold in the queue. In this case immediately after the end of the current call Mr. Jackson takes the earliest incoming call from the queue and starts the conversation. If Mr. Jackson started the call at the second <span class=\"tex-span\"><i>t</i></span>, and the call continues for <span class=\"tex-span\"><i>d</i></span> seconds, then Mr. Jackson is busy at seconds <span class=\"tex-span\"><i>t</i>, <i>t</i> + 1, ..., <i>t</i> + <i>d</i> - 1</span>, and he can start a new call at second <span class=\"tex-span\"><i>t</i> + <i>d</i></span>. Note that if Mr. Jackson is not busy talking when somebody calls, he can't put this call on hold.</p><p>Mr. Jackson isn't Napoleon either, he likes to sleep. So sometimes he allows himself the luxury of ignoring a call, as if it never was scheduled. He can ignore at most <span class=\"tex-span\"><i>k</i></span> calls. Note that a call which comes while he is busy talking can be ignored as well.</p><p>What is the maximum number of seconds Mr. Jackson can sleep today, assuming that he can choose an arbitrary continuous time segment from the current day (that is, with seconds from the 1-st to the 86400-th, inclusive) when he is not busy talking?</p><p>Note that some calls can be continued or postponed to the next day or even later. However, the interval for sleep should be completely within the current day.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains a pair of integers <span class=\"tex-span\"><i>n</i></span>, <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">0 ≤ <i>k</i> ≤ <i>n</i> ≤ 4000</span>) separated by a space. Following <span class=\"tex-span\"><i>n</i></span> lines contain the description of calls for today. The description of each call is located on the single line and consists of two space-separated integers <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>d</i><sub class=\"lower-index\"><i>i</i></sub></span>, (<span class=\"tex-span\">1 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub>, <i>d</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 86400</span>). All <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> are distinct, the calls are given in the order of strict increasing <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>Scheduled times of calls [<span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub> + <i>d</i><sub class=\"lower-index\"><i>i</i></sub> - 1</span>] can arbitrarily intersect.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a number from 0 to 86400, inclusive — the maximally possible number of seconds for Mr. Jackson to sleep today.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 2<br />30000 15000<br />40000 15000<br />50000 15000<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>49999<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>5 1<br />1 20000<br />10000 10000<br />20000 20000<br />25000 10000<br />80000 60000<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>39999<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample the most convenient way is to ignore the first two calls.</p><p>In the second sample it is best to ignore the third call. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":783,"cells":{"problem_id":{"kind":"string","value":"159A"},"contest":{"kind":"string","value":"159"},"problem":{"kind":"string","value":"A"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"A. Friends or Not"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Friends or Not</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Polycarpus has a hobby — he develops an unusual social network. His work is almost completed, and there is only one more module to implement — the module which determines friends. Oh yes, in this social network one won't have to add friends manually! Pairs of friends are deduced in the following way. Let's assume that user <span class=\"tex-span\"><i>A</i></span> sent user <span class=\"tex-span\"><i>B</i></span> a message at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">1</sub></span>, and user <span class=\"tex-span\"><i>B</i></span> sent user <span class=\"tex-span\"><i>A</i></span> a message at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">2</sub></span>. If <span class=\"tex-span\">0 < <i>t</i><sub class=\"lower-index\">2</sub> - <i>t</i><sub class=\"lower-index\">1</sub> ≤ <i>d</i></span>, then user <span class=\"tex-span\"><i>B</i></span>'s message was <span class=\"tex-font-style-it\">an answer</span> to user <span class=\"tex-span\"><i>A</i></span>'s one. Users <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> are considered to be friends if <span class=\"tex-span\"><i>A</i></span> answered at least one <span class=\"tex-span\"><i>B</i></span>'s message or <span class=\"tex-span\"><i>B</i></span> answered at least one <span class=\"tex-span\"><i>A</i></span>'s message.</p><p>You are given the log of messages in chronological order and a number <span class=\"tex-span\"><i>d</i></span>. Find all pairs of users who will be considered to be friends.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>d</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>d</i> ≤ 1000</span>). The next <span class=\"tex-span\"><i>n</i></span> lines contain the messages log. The <span class=\"tex-span\"><i>i</i></span>-th line contains one line of the log formatted as \"<span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), which means that user <span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> sent a message to user <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>). <span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> are non-empty strings at most <span class=\"tex-span\">20</span> characters long, consisting of lowercase letters ('<span class=\"tex-font-style-tt\">a</span>' ... '<span class=\"tex-font-style-tt\">z</span>'), and <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer (<span class=\"tex-span\">0 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10000</span>). It is guaranteed that the lines are given in non-decreasing order of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>'s and that no user sent a message to himself. The elements in the lines are separated by single spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print integer <span class=\"tex-span\"><i>k</i></span> — the number of pairs of friends. In the next <span class=\"tex-span\"><i>k</i></span> lines print pairs of friends as \"<span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes). You can print users in pairs and the pairs themselves in any order. Each pair must be printed exactly once.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br/>vasya petya 1<br/>petya vasya 2<br/>anya ivan 2<br/>ivan anya 4<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/>petya vasya<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1 1000<br/>a b 0<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample test case Vasya and Petya are friends because their messages' sending times are one second apart. Anya and Ivan are not, because their messages' sending times differ by more than one second.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"79665241f1c34b22e642b0ff98065738\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - A - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"e50bacfbba7087a74fb4541fbac381af3f846e76\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - A - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"A\" data-uuid=\"ps_09e8a9d55ee385b187e30b3b1c228c52167377a0\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Friends or Not</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Polycarpus has a hobby — he develops an unusual social network. His work is almost completed, and there is only one more module to implement — the module which determines friends. Oh yes, in this social network one won't have to add friends manually! Pairs of friends are deduced in the following way. Let's assume that user <span class=\"tex-span\"><i>A</i></span> sent user <span class=\"tex-span\"><i>B</i></span> a message at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">1</sub></span>, and user <span class=\"tex-span\"><i>B</i></span> sent user <span class=\"tex-span\"><i>A</i></span> a message at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\">2</sub></span>. If <span class=\"tex-span\">0 < <i>t</i><sub class=\"lower-index\">2</sub> - <i>t</i><sub class=\"lower-index\">1</sub> ≤ <i>d</i></span>, then user <span class=\"tex-span\"><i>B</i></span>'s message was <span class=\"tex-font-style-it\">an answer</span> to user <span class=\"tex-span\"><i>A</i></span>'s one. Users <span class=\"tex-span\"><i>A</i></span> and <span class=\"tex-span\"><i>B</i></span> are considered to be friends if <span class=\"tex-span\"><i>A</i></span> answered at least one <span class=\"tex-span\"><i>B</i></span>'s message or <span class=\"tex-span\"><i>B</i></span> answered at least one <span class=\"tex-span\"><i>A</i></span>'s message.</p><p>You are given the log of messages in chronological order and a number <span class=\"tex-span\"><i>d</i></span>. Find all pairs of users who will be considered to be friends.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of the input contains two integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>d</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>d</i> ≤ 1000</span>). The next <span class=\"tex-span\"><i>n</i></span> lines contain the messages log. The <span class=\"tex-span\"><i>i</i></span>-th line contains one line of the log formatted as "<span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), which means that user <span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> sent a message to user <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> at time <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>n</i></span>). <span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span> are non-empty strings at most <span class=\"tex-span\">20</span> characters long, consisting of lowercase letters ('<span class=\"tex-font-style-tt\">a</span>' ... '<span class=\"tex-font-style-tt\">z</span>'), and <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span> is an integer (<span class=\"tex-span\">0 ≤ <i>t</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10000</span>). It is guaranteed that the lines are given in non-decreasing order of <span class=\"tex-span\"><i>t</i><sub class=\"lower-index\"><i>i</i></sub></span>'s and that no user sent a message to himself. The elements in the lines are separated by single spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the first line print integer <span class=\"tex-span\"><i>k</i></span> — the number of pairs of friends. In the next <span class=\"tex-span\"><i>k</i></span> lines print pairs of friends as "<span class=\"tex-span\"><i>A</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>B</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes). You can print users in pairs and the pairs themselves in any order. Each pair must be printed exactly once.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4 1<br />vasya petya 1<br />petya vasya 2<br />anya ivan 2<br />ivan anya 4<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br />petya vasya<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1 1000<br />a b 0<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample test case Vasya and Petya are friends because their messages' sending times are one second apart. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":784,"cells":{"problem_id":{"kind":"string","value":"159B"},"contest":{"kind":"string","value":"159"},"problem":{"kind":"string","value":"B"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"B. Matchmaker"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Matchmaker</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Polycarpus has <span class=\"tex-span\"><i>n</i></span> markers and <span class=\"tex-span\"><i>m</i></span> marker caps. Each marker is described by two numbers: <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> is the color and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> is the diameter. Correspondingly, each cap is described by two numbers: <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub></span> is the color and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub></span> is the diameter. Cap <span class=\"tex-span\">(<i>a</i><sub class=\"lower-index\"><i>j</i></sub>, <i>b</i><sub class=\"lower-index\"><i>j</i></sub>)</span> can close marker <span class=\"tex-span\">(<i>x</i><sub class=\"lower-index\"><i>i</i></sub>, <i>y</i><sub class=\"lower-index\"><i>i</i></sub>)</span> only if their diameters match, that is, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub> = <i>y</i><sub class=\"lower-index\"><i>i</i></sub></span>. Besides, a marker is considered to be <span class=\"tex-font-style-it\">beautifully closed</span>, if the cap color and the marker color match, that is, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub> = <i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>Find the way to close the maximum number of markers. If there are several such ways, then choose the one that has the maximum number of <span class=\"tex-font-style-it\">beautifully closed</span> markers.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of markers and the number of caps, correspondingly. </p><p>Next <span class=\"tex-span\"><i>n</i></span> lines describe the markers. The <span class=\"tex-span\"><i>i</i></span>-th line contains two space-separated integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub>, <i>y</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>) — the <span class=\"tex-span\"><i>i</i></span>-th marker's color and diameter, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines describe the caps. The <span class=\"tex-span\"><i>j</i></span>-th line contains two space-separated integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub></span>, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>j</i></sub>, <i>b</i><sub class=\"lower-index\"><i>j</i></sub> ≤ 1000</span>) — the color and diameter of the <span class=\"tex-span\"><i>j</i></span>-th cap, correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print two space-separated integers <span class=\"tex-span\"><i>u</i>, <i>v</i></span>, where <span class=\"tex-span\"><i>u</i></span> is the number of closed markers and <span class=\"tex-span\"><i>v</i></span> is the number of <span class=\"tex-font-style-it\">beautifully closed</span> markers in the sought optimal way. Remember that you have to find the way to close the maximum number of markers, and if there are several such ways, you should choose the one where the number of <span class=\"tex-font-style-it\">beautifully closed</span> markers is maximum.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 4<br/>1 2<br/>3 4<br/>2 4<br/>5 4<br/>2 4<br/>1 1<br/>1 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3 2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2 2<br/>1 2<br/>2 1<br/>3 4<br/>5 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1 0<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test sample the first marker should be closed by the fourth cap, the second marker should be closed by the first cap and the third marker should be closed by the second cap. Thus, three markers will be closed, and two of them will be <span class=\"tex-font-style-it\">beautifully closed</span> — the first and the third markers.</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"b5ec461c040f152d62d16e945a12b187\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - B - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"e50bacfbba7087a74fb4541fbac381af3f846e76\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - B - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/159\">VK Cup 2012 Qualification Round 2</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"B\" data-uuid=\"ps_b9c82842eb7ea747fd04b9a14119170a8529fa08\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">B. Matchmaker</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Polycarpus has <span class=\"tex-span\"><i>n</i></span> markers and <span class=\"tex-span\"><i>m</i></span> marker caps. Each marker is described by two numbers: <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span> is the color and <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> is the diameter. Correspondingly, each cap is described by two numbers: <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub></span> is the color and <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub></span> is the diameter. Cap <span class=\"tex-span\">(<i>a</i><sub class=\"lower-index\"><i>j</i></sub>, <i>b</i><sub class=\"lower-index\"><i>j</i></sub>)</span> can close marker <span class=\"tex-span\">(<i>x</i><sub class=\"lower-index\"><i>i</i></sub>, <i>y</i><sub class=\"lower-index\"><i>i</i></sub>)</span> only if their diameters match, that is, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub> = <i>y</i><sub class=\"lower-index\"><i>i</i></sub></span>. Besides, a marker is considered to be <span class=\"tex-font-style-it\">beautifully closed</span>, if the cap color and the marker color match, that is, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub> = <i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>.</p><p>Find the way to close the maximum number of markers. If there are several such ways, then choose the one that has the maximum number of <span class=\"tex-font-style-it\">beautifully closed</span> markers.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first input line contains two space-separated integers <span class=\"tex-span\"><i>n</i></span> and <span class=\"tex-span\"><i>m</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i>, <i>m</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of markers and the number of caps, correspondingly. </p><p>Next <span class=\"tex-span\"><i>n</i></span> lines describe the markers. The <span class=\"tex-span\"><i>i</i></span>-th line contains two space-separated integers <span class=\"tex-span\"><i>x</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>y</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>x</i><sub class=\"lower-index\"><i>i</i></sub>, <i>y</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 1000</span>) — the <span class=\"tex-span\"><i>i</i></span>-th marker's color and diameter, correspondingly.</p><p>Next <span class=\"tex-span\"><i>m</i></span> lines describe the caps. The <span class=\"tex-span\"><i>j</i></span>-th line contains two space-separated integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>j</i></sub></span>, <span class=\"tex-span\"><i>b</i><sub class=\"lower-index\"><i>j</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>j</i></sub>, <i>b</i><sub class=\"lower-index\"><i>j</i></sub> ≤ 1000</span>) — the color and diameter of the <span class=\"tex-span\"><i>j</i></span>-th cap, correspondingly.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print two space-separated integers <span class=\"tex-span\"><i>u</i>, <i>v</i></span>, where <span class=\"tex-span\"><i>u</i></span> is the number of closed markers and <span class=\"tex-span\"><i>v</i></span> is the number of <span class=\"tex-font-style-it\">beautifully closed</span> markers in the sought optimal way. Remember that you have to find the way to close the maximum number of markers, and if there are several such ways, you should choose the one where the number of <span class=\"tex-font-style-it\">beautifully closed</span> markers is maximum.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>3 4<br />1 2<br />3 4<br />2 4<br />5 4<br />2 4<br />1 1<br />1 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>3 2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2 2<br />1 2<br />2 1<br />3 4<br />5 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1 0<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first test sample the first marker should be closed by the fourth cap, the second marker should be closed by the first cap and the third marker should be closed by the second cap. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:13</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. 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none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n </label>\r\n </div>\r\n <div style=\"padding: 0 1em 1em 1em;text-align:right;\">\r\n <input style=\"height:1.65em;padding:0 0.75em;\" type=\"submit\" value=\"Find\"/>\r\n </div>\r\n </form>\r\n </div>\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".handleBox\").autocomplete(\"/data/handles\", {\r\n delay: 200,\r\n width: 200,\r\n selectFirst: false,\r\n matchContains: true,\r\n minChars: 3\r\n });\r\n $(\".handleForm\").attr(\"autocomplete\", \"off\").submit(function () {\r\n var link = \"/profile/userHandle\".replace(\r\n \"userHandle\", $(this).find(\".handleBox\").val()\r\n );\r\n window.location = link;\r\n return false;\r\n });\r\n });\n </script>\n\r\n\r\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Recent actions\n <div class=\"top-links\">\n </div>\n </div>\n <div class=\"recent-actions\">\r\n <ul>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/.Danet\" title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pranshu_Pandya\" title=\"Specialist Pranshu_Pandya\" class=\"rated-user user-cyan\">Pranshu_Pandya</a> →\r\n <a href=\"/blog/entry/121171\">An Interesting Tree Problem</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/sszcdjr\" title=\"Master sszcdjr\" class=\"rated-user user-orange\">sszcdjr</a> →\r\n <a href=\"/blog/entry/119859\">Codeforces Round 896 (Div. 1, Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/yeon_gist\" title=\"Newbie yeon_gist\" class=\"rated-user user-gray\">yeon_gist</a> →\r\n <a href=\"/blog/entry/121170\">plusMinusPermutation computing error</a>\r\n <img alt=\"Text created or updated\" title=\"Text created or updated\" src=\"//codeforces.org/s/81027/images/icons/x-update-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/altforminuscontribution\" title=\"Newbie altforminuscontribution\" class=\"rated-user user-gray\">altforminuscontribution</a> →\r\n <a href=\"/blog/entry/121162\">My screen get unexpectedly big, what should I do</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/atcoder_official\" title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/dino_merlin\" title=\"Expert dino_merlin\" class=\"rated-user user-blue\">dino_merlin</a> →\r\n <a href=\"/blog/entry/121145\">Intuitive approach for CEOI Kangaroo?</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/icecuber\" title=\"Grandmaster icecuber\" class=\"rated-user user-red\">icecuber</a> →\r\n <a href=\"/blog/entry/70018\">CSES DP section editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":785,"cells":{"problem_id":{"kind":"string","value":"159C"},"contest":{"kind":"string","value":"159"},"problem":{"kind":"string","value":"C"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"C. String Manipulation 1.0"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. String Manipulation 1.0</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One popular website developed an unusual username editing procedure. One can change the username only by deleting some characters from it: to change the current name <span class=\"tex-span\"><i>s</i></span>, a user can pick number <span class=\"tex-span\"><i>p</i></span> and character <span class=\"tex-span\"><i>c</i></span> and delete the <span class=\"tex-span\"><i>p</i></span>-th occurrence of character <span class=\"tex-span\"><i>c</i></span> from the name. After the user changed his name, he can't undo the change.</p><p>For example, one can change name \"<span class=\"tex-font-style-tt\">arca</span>\" by removing the second occurrence of character \"<span class=\"tex-font-style-tt\">a</span>\" to get \"<span class=\"tex-font-style-tt\">arc</span>\". </p><p>Polycarpus learned that some user initially registered under nickname <span class=\"tex-span\"><i>t</i></span>, where <span class=\"tex-span\"><i>t</i></span> is a concatenation of <span class=\"tex-span\"><i>k</i></span> copies of string <span class=\"tex-span\"><i>s</i></span>. Also, Polycarpus knows the sequence of this user's name changes. Help Polycarpus figure out the user's final name.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ 2000</span>). The second line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters, at most <span class=\"tex-span\">100</span> characters long. The third line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">0 ≤ <i>n</i> ≤ 20000</span>) — the number of username changes. Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains the actual changes, one per line. The changes are written as \"<span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>\" (without the quotes), where <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 200000</span>) is the number of occurrences of letter <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> is a lowercase Latin letter. It is guaranteed that the operations are correct, that is, the letter to be deleted always exists, and after all operations not all letters are deleted from the name. The letters' occurrences are numbered starting from 1.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single string — the user's final name after all changes are applied to it.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>bac<br/>3<br/>2 a<br/>1 b<br/>2 c<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>acb<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br/>abacaba<br/>4<br/>1 a<br/>1 a<br/>1 c<br/>2 b<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>baa<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Let's consider the first sample. Initially we have name \"<span class=\"tex-font-style-tt\">bacbac</span>\"; the first operation transforms it into \"<span class=\"tex-font-style-tt\">bacbc</span>\", the second one — to \"<span class=\"tex-font-style-tt\">acbc</span>\", and finally, the third one transforms it into \"<span class=\"tex-font-style-tt\">acb</span>\".</p></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"d1b28b2c0dbaa4f6db6edae4d3b399eb\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - C - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"e50bacfbba7087a74fb4541fbac381af3f846e76\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - C - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.\r\n </div>\r\n </div>\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:100%;\"><a style=\"color: black\" href=\"/contest/159\">VK Cup 2012 Qualification Round 2</a></th>\n </tr>\n <tr>\n <td class=\"left bottom\" colspan=\"1\"><span class=\"contest-state-phase\">Finished</span></td>\n </tr>\n </tbody>\n </table>\n </div>\n\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Practice?\n <div class=\"top-links\">\n </div>\n </div>\n<div>\r\n <div style=\"margin:1em;font-size:0.8em;\">\r\n Want to solve the contest problems after the official contest ends? 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style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Special solving requirements, e.g. unknown programming language, etc.\">\r\n *special problem\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Binary search\">\r\n binary search\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Brute force\">\r\n brute force\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Heaps, binary search trees, segment trees, hash tables, etc\">\r\n data structures\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Prefix- and Z-functions, suffix structures, Knuth–Morris–Pratt algorithm, etc\">\r\n strings\r\n</span>\r\n </div>\n\n <div class=\"roundbox borderTopRound borderBottomRound\" style=\"margin:2px; padding:0 3px 2px 3px; background-color:#f0f0f0;float:left;\">\n<span class=\"tag-box\" style=\"font-size:1.2rem;\" title=\"Difficulty\">\r\n *1400\r\n</span>\r\n </div>\n <div style=\"clear:both;text-align:right;font-size:1.1rem;\">\r\n <span title=\"Please login into the Codeforces\" class=\"notice\">No tag edit access</span>\r\n </div>\r\n</div>\r\n </div>\n\r\n<form id=\"addTagForm\" action=\"/data/problemTags\" method=\"post\" style=\"display:none;\"><input type='hidden' name='csrf_token' 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monospace;\r\n}\r\n</style>\r\n<div class=\"roundbox sidebox sidebar-menu borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Contest materials\n<div class=\"top-links\">\n</div>\n</div>\n<ul>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4072\" title=\"VK Cup 2012 Qualification Round 2\" target=\"_blank\">Announcement</a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"629:630\" resourceName=\"Announcement\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n<li>\r\n<span>\r\n<a href=\"/blog/entry/4089\" title=\"Simple solution to vk cup Qualification Round 1 and 2\" target=\"_blank\">Tutorial <span class=\"resource-locale\">(en)</span></a>\r\n</span>\r\n<span style=\"float: right;\">\r\n<img class=\"delete-resource-link\" resourceIds=\"631\" resourceName=\"Simple solution to vk cup Qualification Round 1 and 2\"\r\nresourceManual=\"true\" src=\"//codeforces.org/s/73366/images/icons/close-10x10.png\"\r\nstyle=\"position: relative;bottom: -1px;left: 1px;cursor: pointer;\"/>\r\n</span>\r\n<div style=\"clear: both;\"></div>\r\n</li>\r\n</ul>\r\n</div></div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li class=\"current selectedLava\"><a\r\n href=\"/contest/159\">Problems</a></li>\r\n <li><a\r\n href=\"/contest/159/submit\">Submit Code</a></li>\r\n <li><a\r\n href=\"/contest/159/my\">My Submissions</a></li>\r\n <li><a\r\n href=\"/contest/159/status\">Status</a></li>\r\n <li><a\r\n href=\"/contest/159/standings\">Standings</a></li>\r\n <li><a\r\n href=\"/contest/159/customtest\">Custom Invocation</a></li>\r\n</ul>\r\n</div>\n\r\n <style>\r\n #facebox .content:has(.diff-popup) {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n }\r\n\r\n .testCaseMarker {\r\n position: absolute;\r\n font-weight: bold;\r\n font-size: 1rem;\r\n }\r\n\r\n .diff-popup {\r\n width: 90vw;\r\n max-width: 120rem !important;\r\n display: none;\r\n overflow: auto;\r\n }\r\n\r\n .input-output-copier {\r\n font-size: 1.2rem;\r\n float: right;\r\n color: #888 !important;\r\n cursor: pointer;\r\n border: 1px solid rgb(185, 185, 185);\r\n padding: 3px;\r\n margin: 1px;\r\n line-height: 1.1rem;\r\n text-transform: none;\r\n }\r\n\r\n .input-output-copier:hover {\r\n background-color: #def;\r\n }\r\n\r\n .test-explanation textarea {\r\n width: 100%;\r\n height: 1.5em;\r\n }\r\n\r\n .pending-submission-message {\r\n color: darkorange !important;\r\n }\r\n </style>\r\n <script>\r\n const OPENING_SPACE = String.fromCharCode(1001);\r\n const CLOSING_SPACE = String.fromCharCode(1002);\r\n\r\n const nodeToText = function (node, pre) {\r\n let result = [];\r\n\r\n if (node.tagName === \"SCRIPT\" || node.tagName === \"math\"\r\n || (node.classList && node.classList.contains(\"input-output-copier\")))\r\n return [];\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(OPENING_SPACE);\r\n }\r\n\r\n if (node.nodeType === Node.TEXT_NODE) {\r\n let s = node.textContent;\r\n if (!pre) {\r\n s = s.replace(/\\s+/g, \" \");\r\n }\r\n if (s.length > 0) {\r\n result.push(s);\r\n }\r\n }\r\n\r\n if (pre && node.tagName === \"BR\") {\r\n result.push(\"\\n\");\r\n }\r\n\r\n node.childNodes.forEach(function (child) {\r\n result.push(nodeToText(child, node.tagName === \"PRE\").join(\"\"));\r\n });\r\n\r\n if (node.tagName === \"DIV\"\r\n || node.tagName === \"P\"\r\n || node.tagName === \"PRE\"\r\n || node.tagName === \"UL\"\r\n || node.tagName === \"LI\"\r\n ) {\r\n result.push(\"\\n\");\r\n }\r\n\r\n if (node.tagName === \"NOBR\") {\r\n result.push(CLOSING_SPACE);\r\n }\r\n\r\n return result;\r\n }\r\n\r\n const isSpecial = function (c) {\r\n return c === ',' || c === '.' || c === ';' || c === ')' || c === ' ';\r\n }\r\n\r\n const convertStatementToText = function(statmentNode) {\r\n const text = nodeToText(statmentNode, false).join(\"\").replace(/ +/g, \" \").replace(/\\n\\n+/g, \"\\n\\n\");\r\n let result = [];\r\n for (let i = 0; i < text.length; i++) {\r\n const c = text.charAt(i);\r\n if (c === OPENING_SPACE) {\r\n if (!((i > 0 && text.charAt(i - 1) === '(') || (result.length > 0 && result[result.length - 1] === ' '))) {\r\n result.push('+');\r\n }\r\n } else if (c === CLOSING_SPACE) {\r\n if (!(i + 1 < text.length && isSpecial(text.charAt(i + 1)))) {\r\n result.push('-');\r\n }\r\n } else {\r\n result.push(c);\r\n }\r\n }\r\n return result.join(\"\").split(\"\\n\").map(value => value.trim()).join(\"\\n\");\r\n };\r\n </script>\r\n <div class=\"diff-popup\">\r\n </div>\r\n\r\n<div class=\"problemindexholder\" problemindex=\"C\" data-uuid=\"ps_15b86118fd98790c6c6c3caaec7eb622eb5560d9\">\r\n <div style=\"display: none; margin:1em 0;text-align: center; position: relative;\" class=\"alert alert-info diff-notifier\">\r\n <div>The problem statement has recently been changed. <a class=\"view-changes\" href=\"#\">View the changes.</a></div>\r\n <span class=\"diff-notifier-close\" style=\"position: absolute; top: 0.2em; right: 0.3em; cursor: pointer; font-size: 1.4em;\">×</span>\r\n </div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">C. String Manipulation 1.0</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>One popular website developed an unusual username editing procedure. One can change the username only by deleting some characters from it: to change the current name <span class=\"tex-span\"><i>s</i></span>, a user can pick number <span class=\"tex-span\"><i>p</i></span> and character <span class=\"tex-span\"><i>c</i></span> and delete the <span class=\"tex-span\"><i>p</i></span>-th occurrence of character <span class=\"tex-span\"><i>c</i></span> from the name. After the user changed his name, he can't undo the change.</p><p>For example, one can change name "<span class=\"tex-font-style-tt\">arca</span>" by removing the second occurrence of character "<span class=\"tex-font-style-tt\">a</span>" to get "<span class=\"tex-font-style-tt\">arc</span>". </p><p>Polycarpus learned that some user initially registered under nickname <span class=\"tex-span\"><i>t</i></span>, where <span class=\"tex-span\"><i>t</i></span> is a concatenation of <span class=\"tex-span\"><i>k</i></span> copies of string <span class=\"tex-span\"><i>s</i></span>. Also, Polycarpus knows the sequence of this user's name changes. Help Polycarpus figure out the user's final name.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>k</i></span> (<span class=\"tex-span\">1 ≤ <i>k</i> ≤ 2000</span>). The second line contains a non-empty string <span class=\"tex-span\"><i>s</i></span>, consisting of lowercase Latin letters, at most <span class=\"tex-span\">100</span> characters long. The third line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">0 ≤ <i>n</i> ≤ 20000</span>) — the number of username changes. Each of the next <span class=\"tex-span\"><i>n</i></span> lines contains the actual changes, one per line. The changes are written as "<span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>" (without the quotes), where <span class=\"tex-span\"><i>p</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>p</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 200000</span>) is the number of occurrences of letter <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span>, <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> is a lowercase Latin letter. It is guaranteed that the operations are correct, that is, the letter to be deleted always exists, and after all operations not all letters are deleted from the name. The letters' occurrences are numbered starting from 1.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print a single string — the user's final name after all changes are applied to it.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />bac<br />3<br />2 a<br />1 b<br />2 c<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>acb<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>1<br />abacaba<br />4<br />1 a<br />1 a<br />1 c<br />2 b<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>baa<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>Let's consider the first sample. 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":786,"cells":{"problem_id":{"kind":"string","value":"159D"},"contest":{"kind":"string","value":"159"},"problem":{"kind":"string","value":"D"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"D. Palindrome pairs"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Palindrome pairs</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You are given a non-empty string <span class=\"tex-span\"><i>s</i></span> consisting of lowercase letters. Find the number of pairs of non-overlapping palindromic substrings of this string.</p><p>In a more formal way, you have to find the quantity of tuples <span class=\"tex-span\">(<i>a</i>, <i>b</i>, <i>x</i>, <i>y</i>)</span> such that <span class=\"tex-span\">1 ≤ <i>a</i> ≤ <i>b</i> < <i>x</i> ≤ <i>y</i> ≤ |<i>s</i>|</span> and substrings <span class=\"tex-span\"><i>s</i>[<i>a</i>... <i>b</i>]</span>, <span class=\"tex-span\"><i>s</i>[<i>x</i>... <i>y</i>]</span> are palindromes.</p><p>A <span class=\"tex-font-style-it\">palindrome</span> is a string that can be read the same way from left to right and from right to left. For example, \"<span class=\"tex-font-style-tt\">abacaba</span>\", \"<span class=\"tex-font-style-tt\">z</span>\", \"<span class=\"tex-font-style-tt\">abba</span>\" are palindromes.</p><p>A <span class=\"tex-font-style-it\">substring</span> <span class=\"tex-span\"><i>s</i>[<i>i</i>... <i>j</i>]</span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>j</i> ≤ |<i>s</i>|</span>) of string <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub><i>s</i><sub class=\"lower-index\">2</sub>... <i>s</i><sub class=\"lower-index\">|<i>s</i>|</sub></span> is a string <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub><i>s</i><sub class=\"lower-index\"><i>i</i> + 1</sub>... <i>s</i><sub class=\"lower-index\"><i>j</i></sub></span>. For example, substring <span class=\"tex-span\"><i>s</i>[2...4]</span> of string <span class=\"tex-span\"><i>s</i></span> = \"<span class=\"tex-font-style-tt\">abacaba</span>\" equals \"<span class=\"tex-font-style-tt\">bac</span>\".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of input contains a non-empty string <span class=\"tex-span\"><i>s</i></span> which consists of lowercase letters ('<span class=\"tex-font-style-tt\">a</span>'...'<span class=\"tex-font-style-tt\">z</span>'), <span class=\"tex-span\"><i>s</i></span> contains at most <span class=\"tex-span\">2000</span> characters.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Output a single number — the quantity of pairs of non-overlapping palindromic substrings of <span class=\"tex-span\"><i>s</i></span>.</p><p>Please do not use the %lld format specifier to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d format specifier.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>aaa<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abacaba<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>36<br/></pre></div></div></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"7a68e41ee4cb144f05ec0178261c7320\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - D - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"e50bacfbba7087a74fb4541fbac381af3f846e76\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - D - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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</div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">D. Palindrome pairs</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>3 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>You are given a non-empty string <span class=\"tex-span\"><i>s</i></span> consisting of lowercase letters. Find the number of pairs of non-overlapping palindromic substrings of this string.</p><p>In a more formal way, you have to find the quantity of tuples <span class=\"tex-span\">(<i>a</i>, <i>b</i>, <i>x</i>, <i>y</i>)</span> such that <span class=\"tex-span\">1 ≤ <i>a</i> ≤ <i>b</i> < <i>x</i> ≤ <i>y</i> ≤ |<i>s</i>|</span> and substrings <span class=\"tex-span\"><i>s</i>[<i>a</i>... <i>b</i>]</span>, <span class=\"tex-span\"><i>s</i>[<i>x</i>... <i>y</i>]</span> are palindromes.</p><p>A <span class=\"tex-font-style-it\">palindrome</span> is a string that can be read the same way from left to right and from right to left. For example, "<span class=\"tex-font-style-tt\">abacaba</span>", "<span class=\"tex-font-style-tt\">z</span>", "<span class=\"tex-font-style-tt\">abba</span>" are palindromes.</p><p>A <span class=\"tex-font-style-it\">substring</span> <span class=\"tex-span\"><i>s</i>[<i>i</i>... <i>j</i>]</span> (<span class=\"tex-span\">1 ≤ <i>i</i> ≤ <i>j</i> ≤ |<i>s</i>|</span>) of string <span class=\"tex-span\"><i>s</i></span> = <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\">1</sub><i>s</i><sub class=\"lower-index\">2</sub>... <i>s</i><sub class=\"lower-index\">|<i>s</i>|</sub></span> is a string <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub><i>s</i><sub class=\"lower-index\"><i>i</i> + 1</sub>... <i>s</i><sub class=\"lower-index\"><i>j</i></sub></span>. For example, substring <span class=\"tex-span\"><i>s</i>[2...4]</span> of string <span class=\"tex-span\"><i>s</i></span> = "<span class=\"tex-font-style-tt\">abacaba</span>" equals "<span class=\"tex-font-style-tt\">bac</span>".</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line of input contains a non-empty string <span class=\"tex-span\"><i>s</i></span> which consists of lowercase letters ('<span class=\"tex-font-style-tt\">a</span>'...'<span class=\"tex-font-style-tt\">z</span>'), <span class=\"tex-span\"><i>s</i></span> contains at most <span class=\"tex-span\">2000</span> characters.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Output a single number — the quantity of pairs of non-overlapping palindromic substrings of <span class=\"tex-span\"><i>s</i></span>.</p><p>Please do not use the %lld format specifier to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d format specifier.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>aa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>1<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>aaa<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>5<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>abacaba<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>36<br /></pre></div></div></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=D]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = convertStatementToText($problem.find(\".ttypography\").get(0));\r\n\r\n let previousStatementText = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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title=\"Expert .Danet\" class=\"rated-user user-blue\">.Danet</a> →\r\n <a href=\"/blog/entry/121172\">[TLE on pretest1]</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/121073\">Meta Hacker Cup 2023 Round 1</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Pyqe\" title=\"International Grandmaster Pyqe\" class=\"rated-user user-red\">Pyqe</a> →\r\n <a href=\"/blog/entry/121025\">Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final 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style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a> →\r\n <a href=\"/blog/entry/119880\">It's Happening! Meta Hacker Cup 2023 Schedule</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/DaviddeGea1\" title=\"Expert DaviddeGea1\" class=\"rated-user user-blue\">DaviddeGea1</a> →\r\n <a href=\"/blog/entry/70917\">Number of ways of dividing an array into 2 parts such that sum of each part is > k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bekh\" title=\"Master Bekh\" class=\"rated-user user-orange\">Bekh</a> →\r\n <a href=\"/blog/entry/74245\">Questions and doubts regarding Aliens DP trick</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/cgy4ever\" title=\"International Grandmaster cgy4ever\" class=\"rated-user user-red\">cgy4ever</a> →\r\n <a href=\"/blog/entry/8192\">Codeforces Round #190 — Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/hocky\" title=\"Candidate Master hocky\" class=\"rated-user user-violet\">hocky</a> →\r\n <a href=\"/blog/entry/95323\">FBHC wuining uw Day? Incwease uw stacc size! (ㅅ´ ˘ `)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/liouzhou_101\" title=\"International Master liouzhou_101\" class=\"rated-user user-orange\">liouzhou_101</a> →\r\n <a href=\"/blog/entry/87598\">Editorial of Codeforces Round #700</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div 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title=\"Unrated, atcoder_official\" class=\"rated-user user-black\">atcoder_official</a> →\r\n <a href=\"/blog/entry/121120\">We will hold UNIQUE VISION Programming Contest 2023 Autumn(AtCoder Beginner Contest 323)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/YouStill_DontKnowMeYet\" title=\"Candidate Master YouStill_DontKnowMeYet\" class=\"rated-user user-violet\">YouStill_DontKnowMeYet</a> →\r\n <a href=\"/blog/entry/117659\">[GYM] Al-Baath Collegiate Programming Contest 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/ankancool\" title=\"Expert ankancool\" class=\"rated-user user-blue\">ankancool</a> →\r\n <a href=\"/blog/entry/121136\">Invitation to AstroByte 2023</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/GeZhiyuan\" title=\"Grandmaster GeZhiyuan\" class=\"rated-user user-red\">GeZhiyuan</a> →\r\n <a href=\"/blog/entry/120943\">Codeforces Round 901 (Div. 1, Div. 2) Editorial</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a> →\r\n <a href=\"/blog/entry/120772\">PSA: Increase your stack size before the Meta Hacker Cup, here's how</a>\r\n <img alt=\"New 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title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Bn00b\" title=\"Newbie Bn00b\" class=\"rated-user user-gray\">Bn00b</a> →\r\n <a href=\"/blog/entry/98820\">[FEATURE REQUEST : ATCODER] TOPICS TAGS AND SORTING BY SOLVE COUNT</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n <img alt=\"Necropost\" title=\"Necropost\" src=\"//codeforces.org/s/81027/images/icons/hourglass.png\" style=\"vertical-align:middle; position: relative; top: 1px;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a> →\r\n <a href=\"/blog/entry/121163\">AtCoder Regular Contest 166 Announcement</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/windva\" title=\"Grandmaster windva\" class=\"rated-user user-red\">windva</a> →\r\n <a href=\"/blog/entry/120644\">Codeforces Round 899 (Div. 2)</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/Misa-Misa\" title=\"Expert Misa-Misa\" class=\"rated-user user-blue\">Misa-Misa</a> →\r\n <a href=\"/blog/entry/121157\">Someone please help me understand this.</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n <li><div style=\"font-size:0.9em;padding:0.5em 0;\">\r\n<a href=\"/profile/shivam565\" title=\"Specialist shivam565\" class=\"rated-user user-cyan\">shivam565</a> →\r\n <a href=\"/blog/entry/108348\">Total number of subarrays with sum atmost k</a>\r\n <img alt=\"New comment(s)\" title=\"New comment(s)\" src=\"//codeforces.org/s/81027/images/icons/comment-12x12.png\" style=\"vertical-align:middle;\"/>\r\n</div>\r\n</li>\r\n </ul>\r\n </div>\r\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/recent-actions\">Detailed →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n</div>\n <div id=\"pageContent\" class=\"content-with-sidebar\">\n <div class=\"second-level-menu\">\r\n<ul class=\"second-level-menu-list\">\r\n <li><a\r\n href=\"/profile/hanfei19910905\">hanfei19910905</a></li>\r\n <li class=\"current selectedLava\"><a\r\n href=\"/blog/hanfei19910905\">Blog</a></li>\r\n <li><a\r\n href=\"/teams/with/hanfei19910905\">Teams</a></li>\r\n <li><a\r\n href=\"/submissions/hanfei19910905\">Submissions</a></li>\r\n <li><a\r\n href=\"/contests/with/hanfei19910905\">Contests</a></li>\r\n</ul>\r\n</div>\n <div style=\"margin-top:0;\">\r\n <div>\r\n <h3><a href=\"/blog/hanfei19910905\" style=\"text-decoration:none;color:black !important;\">hanfei19910905's blog</a></h3>\r\n </div>\r\n <div style=\"margin-top:2em;\">\r\n\r\n\r\n<div class=\"has-topic-id topic\" topicId=\"4103\">\r\n <div class=\"title\">\r\n <a href=\"/blog/entry/4089\"> <p>Simple solution to vk cup Qualification Round 1 and 2</p>\r\n</a>\r\n </div>\r\n\r\n <div class=\"info\" style=\"position:relative;\">\r\n By <a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a>,\r\n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":787,"cells":{"problem_id":{"kind":"string","value":"159E"},"contest":{"kind":"string","value":"159"},"problem":{"kind":"string","value":"E"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"E. Zebra Tower"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Zebra Tower</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>1.5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Little Janet likes playing with cubes. Actually, she likes to play with anything whatsoever, cubes or tesseracts, as long as they are multicolored. Each cube is described by two parameters — color <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and size <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>. A Zebra Tower is a tower that consists of cubes of exactly two colors. Besides, the colors of the cubes in the tower must alternate (colors of adjacent cubes must differ). The Zebra Tower should have at least two cubes. There are no other limitations. The figure below shows an example of a Zebra Tower.</p><center> <img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/7a4c3bedab3921bec40c4a0ccfe322397cc2ed6c.png\" style=\"max-width: 100.0%;max-height: 100.0%;\"/> </center><p>A Zebra Tower's height is the sum of sizes of all cubes that form the tower. Help little Janet build the Zebra Tower of the maximum possible height, using the available cubes.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of cubes. Next <span class=\"tex-span\"><i>n</i></span> lines contain the descriptions of the cubes, one description per line. A cube description consists of two space-separated integers <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub>, <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the <span class=\"tex-span\"><i>i</i></span>-th cube's color and size, correspondingly. It is guaranteed that there are at least two cubes of different colors.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the description of the Zebra Tower of the maximum height in the following form. In the first line print the tower's height, in the second line print the number of cubes that form the tower, and in the third line print the space-separated indices of cubes in the order in which they follow in the tower from the bottom to the top. Assume that the cubes are numbered from 1 to <span class=\"tex-span\"><i>n</i></span> in the order in which they were given in the input.</p><p>If there are several existing Zebra Towers with maximum heights, it is allowed to print any of them. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4<br/>1 2<br/>1 3<br/>2 4<br/>3 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br/>3<br/>2 3 1 <br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>1 1<br/>2 1<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/>2<br/>2 1 <br/></pre></div></div></div></div>"},"page":{"kind":"string","value":"\r\n<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\">\n<html lang=\"en\">\n<head>\n <meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">\n <meta name=\"X-Csrf-Token\" content=\"7502bae6daa992465f2ce582f95c503c\"/>\n <meta id=\"viewport\" name=\"viewport\" content=\"width=device-width, initial-scale=0.01\"/>\n\n\n <script type=\"text/javascript\" src=\"//codeforces.org/s/73366/js/jquery-1.8.3.js\"></script>\n <script type=\"application/javascript\">\n window.locale = \"en\";\n window.standaloneContest = false;\n function adjustViewport() {\n var screenWidthPx = Math.min($(window).width(), window.screen.width);\n var siteWidthPx = 1100; // min width of site\n var ratio = Math.min(screenWidthPx / siteWidthPx, 1.0);\n var viewport = \"width=device-width, initial-scale=\" + ratio;\n $('#viewport').attr('content', viewport);\n var style = $('<style>html * { max-height: 1000000px; }</style>');\n $('html > head').append(style);\n }\n\n if ( /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent) ) {\n adjustViewport();\n }\n\n /* Protection against trailing dot in domain. */\n let hostLength = window.location.host.length;\n if (hostLength > 1 && window.location.host[hostLength - 1] === '.') {\n window.location = window.location.protocol + \"//\" + window.location.host.substring(0, hostLength - 1);\n }\n </script>\n <meta http-equiv=\"pragma\" content=\"no-cache\">\n <meta http-equiv=\"expires\" content=\"-1\">\n <meta http-equiv=\"profileName\" content=\"j3\">\n <meta name=\"google-site-verification\" content=\"OTd2dN5x4nS4OPknPI9JFg36fKxjqY0i1PSfFPv_J90\"/>\n <meta property=\"fb:admins\" content=\"100001352546622\" />\n <meta property=\"og:image\" content=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <link rel=\"image_src\" href=\"//codeforces.org/s/73366/images/codeforces-sponsored-by-ton.png\" />\n <meta property=\"og:title\" content=\"Problem - E - Codeforces\"/>\n <meta property=\"og:description\" content=\"\"/>\n \n <meta property=\"og:site_name\" content=\"Codeforces\"/>\n \n \n \n <meta name=\"cc\" content=\"e50bacfbba7087a74fb4541fbac381af3f846e76\"/>\n \n \n <meta name=\"utc_offset\" content=\"+03:00\"/>\n <meta name=\"verify-reformal\" content=\"f56f99fd7e087fb6ccb48ef2\" />\n <title>Problem - E - Codeforces</title>\n <meta name=\"description\" content=\"Codeforces. 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</div>\r\n <div class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">E. Zebra Tower</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>1.5 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Little Janet likes playing with cubes. Actually, she likes to play with anything whatsoever, cubes or tesseracts, as long as they are multicolored. Each cube is described by two parameters — color <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and size <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span>. A Zebra Tower is a tower that consists of cubes of exactly two colors. Besides, the colors of the cubes in the tower must alternate (colors of adjacent cubes must differ). The Zebra Tower should have at least two cubes. There are no other limitations. The figure below shows an example of a Zebra Tower.</p><center> <img class=\"tex-graphics\" src=\"https://espresso.codeforces.com/7a4c3bedab3921bec40c4a0ccfe322397cc2ed6c.png\" style=\"max-width: 100.0%;max-height: 100.0%;\" /> </center><p>A Zebra Tower's height is the sum of sizes of all cubes that form the tower. Help little Janet build the Zebra Tower of the maximum possible height, using the available cubes.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains an integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">2 ≤ <i>n</i> ≤ 10<sup class=\"upper-index\">5</sup></span>) — the number of cubes. Next <span class=\"tex-span\"><i>n</i></span> lines contain the descriptions of the cubes, one description per line. A cube description consists of two space-separated integers <span class=\"tex-span\"><i>c</i><sub class=\"lower-index\"><i>i</i></sub></span> and <span class=\"tex-span\"><i>s</i><sub class=\"lower-index\"><i>i</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>c</i><sub class=\"lower-index\"><i>i</i></sub>, <i>s</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 10<sup class=\"upper-index\">9</sup></span>) — the <span class=\"tex-span\"><i>i</i></span>-th cube's color and size, correspondingly. It is guaranteed that there are at least two cubes of different colors.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>Print the description of the Zebra Tower of the maximum height in the following form. In the first line print the tower's height, in the second line print the number of cubes that form the tower, and in the third line print the space-separated indices of cubes in the order in which they follow in the tower from the bottom to the top. Assume that the cubes are numbered from 1 to <span class=\"tex-span\"><i>n</i></span> in the order in which they were given in the input.</p><p>If there are several existing Zebra Towers with maximum heights, it is allowed to print any of them. </p><p>Please do not use the <span class=\"tex-font-style-tt\">%lld</span> specificator to read or write 64-bit integers in С++. It is preferred to use the <span class=\"tex-font-style-tt\">cin</span>, <span class=\"tex-font-style-tt\">cout</span> streams or the <span class=\"tex-font-style-tt\">%I64d</span> specificator.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>4<br />1 2<br />1 3<br />2 4<br />3 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>9<br />3<br />2 3 1 <br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />1 1<br />2 1<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br />2<br />2 1 <br /></pre></div></div></div></div></div>\r\n</div>\r\n\r\n <script>\r\n $(function () {\r\n Codeforces.addMathJaxListener(function () {\r\n let $problem = $(\"div[problemindex=E]\");\r\n let uuid = $problem.attr(\"data-uuid\");\r\n let statementText = 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Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n <div style=\"text-align:center;\">\r\n <span class='contest-state-phase'>Before contest</span><br/><a href=\"/contests/1876,1877\">Codeforces Round 902 (Div. 2, based on COMPFEST 15 - Final Round)</a><br/><span class='countdown' home='//codeforces.org/s/81027' noRedirection='true' textBeforeRedirect=''>13:55:13</span><br/><a href=\"/contestRegistration/1877\">Register now »</a><div class=\"smaller notice\">*has extra registration<i class=\"icon-question-sign clickable-title\" title=\"If you are late to register in 5 minutes before the start, you can register later during the extra registration. Extra registration opens 10 minutes after the contest starts and lasts 25 minutes.\"></i></div>\r\n </div>\r\n</div>\r\n </div>\n\n<style data-nocturne=\"true\" type=\"text/css\">\n._StreamsSidebarFrame_frame {\n padding: 0.5em 0.5em 0 0.5em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream {\n text-align: center;\n border-bottom: 1px solid #b9b9b9;\n margin: 0 -0.5em 0.5em -0.5em;\n padding: 0 1em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_user {\n margin: 0 0 0.5em 0;\n font-size: 0.8em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream ._StreamsSidebarFrame_timeMark {\n color: #777;\n font-size: 0.9em;\n}\n._StreamsSidebarFrame_frame ._StreamsSidebarFrame_stream:last-of-type {\n border-bottom: unset;\n margin: unset;\n padding: 0 0.5em 0.5em 1em;\n}\n._StreamsSidebarFrame_frame ._viewAll {\n text-align: right;\n}\n.moreRunningStreamsSidebarNote {\n color: #777 !important;\n text-decoration: none;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n\n}); </script>\n\n<div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n<div class=\"caption titled\">→ Top rated\n<div class=\"top-links\">\n</div>\n</div>\n<table class=\"rtable \">\n<tbody>\n<tr>\n<th class=\"left\" style=\"width:2.25em;\">#</th>\n<th class=\"\">User</th>\n<th class=\"\" style=\"width:5em;\">Rating</th>\n</tr>\n<tr>\n<td class=\"left dark\">1</td>\n<td class=\" dark\"><a href=\"/profile/tourist\" title=\"Legendary Grandmaster tourist\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">t</span>ourist</a></td>\n<td class=\" dark\">3775</td>\n</tr>\n<tr>\n<td class=\"left \">2</td>\n<td class=\"\"><a href=\"/profile/Benq\" title=\"Legendary Grandmaster Benq\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">B</span>enq</a></td>\n<td class=\"\">3724</td>\n</tr>\n<tr>\n<td class=\"left dark\">3</td>\n<td class=\" dark\"><a href=\"/profile/orzdevinwang\" title=\"Legendary Grandmaster orzdevinwang\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">o</span>rzdevinwang</a></td>\n<td class=\" dark\">3697</td>\n</tr>\n<tr>\n<td class=\"left \">4</td>\n<td class=\"\"><a href=\"/profile/Radewoosh\" title=\"Legendary Grandmaster Radewoosh\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>adewoosh</a></td>\n<td class=\"\">3651</td>\n</tr>\n<tr>\n<td class=\"left dark\">5</td>\n<td class=\" dark\"><a href=\"/profile/jiangly\" title=\"Legendary Grandmaster jiangly\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">j</span>iangly</a></td>\n<td class=\" dark\">3632</td>\n</tr>\n<tr>\n<td class=\"left \">6</td>\n<td class=\"\"><a href=\"/profile/cnnfls_csy\" title=\"Legendary Grandmaster cnnfls_csy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">c</span>nnfls_csy</a></td>\n<td class=\"\">3620</td>\n</tr>\n<tr>\n<td class=\"left dark\">7</td>\n<td class=\" dark\"><a href=\"/profile/-0.5\" title=\"Legendary Grandmaster -0.5\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">-</span>0.5</a></td>\n<td class=\" dark\">3545</td>\n</tr>\n<tr>\n<td class=\"left \">8</td>\n<td class=\"\"><a href=\"/profile/inaFSTream\" title=\"Legendary Grandmaster inaFSTream\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">i</span>naFSTream</a></td>\n<td class=\"\">3478</td>\n</tr>\n<tr>\n<td class=\"left dark\">9</td>\n<td class=\" dark\"><a href=\"/profile/fantasy\" title=\"Legendary Grandmaster fantasy\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">f</span>antasy</a></td>\n<td class=\" dark\">3468</td>\n</tr>\n<tr>\n<td class=\"left bottom\">10</td>\n<td class=\"bottom\"><a href=\"/profile/Rebelz\" title=\"Legendary Grandmaster Rebelz\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">R</span>ebelz</a></td>\n<td class=\"bottom\">3415</td>\n</tr>\n</tbody>\n</table>\n<div class=\"bottom-links\">\n<table style=\"width:100%;\">\n<tbody>\n<tr>\n<td style=\"text-align:left;\">\n<a href=\"/ratings/countries\">Countries</a> |\n<a href=\"/ratings/cities\">Cities</a> |\n<a href=\"/ratings/organizations\">Organizations</a>\n</td>\n<td style=\"text-align:right;\">\n<a href=\"/ratings\">View all →</a>\n</td>\n</tr>\n</tbody>\n</table>\n</div>\n</div><div class=\"roundbox sidebox top-contributed borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Top contributors\n <div class=\"top-links\">\n </div>\n </div>\n <table class=\"rtable \">\n <tbody>\n <tr>\n <th class=\"left\" style=\"width:2.25em;\">#</th>\n <th class=\"\">User</th>\n <th class=\"\" style=\"width:5em;\">Contrib.</th>\n </tr>\n <tr>\n <td class=\"left dark\">1</td>\n <td class=\" dark\"><a href=\"/profile/adamant\" title=\"Grandmaster adamant\" class=\"rated-user user-red\">adamant</a></td>\n <td class=\" dark\">178</td>\n </tr>\n <tr>\n <td class=\"left \">2</td>\n <td class=\"\"><a href=\"/profile/awoo\" title=\"Master awoo\" class=\"rated-user user-orange\">awoo</a></td>\n <td class=\"\">167</td>\n </tr>\n <tr>\n <td class=\"left dark\">3</td>\n <td class=\" dark\"><a href=\"/profile/BledDest\" title=\"International Grandmaster BledDest\" class=\"rated-user user-red\">BledDest</a></td>\n <td class=\" dark\">165</td>\n </tr>\n <tr>\n <td class=\"left \">4</td>\n <td class=\"\"><a href=\"/profile/Um_nik\" title=\"Legendary Grandmaster Um_nik\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">U</span>m_nik</a></td>\n <td class=\"\">163</td>\n </tr>\n <tr>\n <td class=\"left dark\">5</td>\n <td class=\" dark\"><a href=\"/profile/maroonrk\" title=\"Legendary Grandmaster maroonrk\" class=\"rated-user user-legendary\"><span class=\"legendary-user-first-letter\">m</span>aroonrk</a></td>\n <td class=\" dark\">162</td>\n </tr>\n <tr>\n <td class=\"left \">6</td>\n <td class=\"\"><a href=\"/profile/SecondThread\" title=\"Master SecondThread\" class=\"rated-user user-orange\">SecondThread</a></td>\n <td class=\"\">160</td>\n </tr>\n <tr>\n <td class=\"left dark\">7</td>\n <td class=\" dark\"><a href=\"/profile/nor\" title=\"Master nor\" class=\"rated-user user-orange\">nor</a></td>\n <td class=\" dark\">158</td>\n </tr>\n <tr>\n <td class=\"left \">8</td>\n <td class=\"\"><a href=\"/profile/-is-this-fft-\" title=\"Grandmaster -is-this-fft-\" class=\"rated-user user-red\">-is-this-fft-</a></td>\n <td class=\"\">152</td>\n </tr>\n <tr>\n <td class=\"left dark\">9</td>\n <td class=\" dark\"><a href=\"/profile/kostka\" title=\"International Grandmaster kostka\" class=\"rated-user user-red\">kostka</a></td>\n <td class=\" dark\">145</td>\n </tr>\n <tr>\n <td class=\"left bottom\">10</td>\n <td class=\"bottom\"><a href=\"/profile/TheScrasse\" title=\"International Grandmaster TheScrasse\" class=\"rated-user user-red\">TheScrasse</a></td>\n <td class=\"bottom\">144</td>\n </tr>\n </tbody>\n </table>\n <div class=\"bottom-links\">\n <table style=\"width:100%;\">\n <tbody>\n <tr>\n <td style=\"text-align:left;\">\n </td>\n <td style=\"text-align:right;\">\n <a href=\"/top-contributed\">View all →</a>\n </td>\n </tr>\n </tbody>\n </table>\n </div>\n </div>\n\r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n });\n </script>\r\n\r\n\n <div class=\"roundbox sidebox borderTopRound \" style=\"\">\n <div class=\"caption titled\">→ Find user\n <div class=\"top-links\">\n </div>\n </div>\n <form class=\"handleForm\" method=\"post\"><input type='hidden' name='csrf_token' value='774ea9adf87964fdd14d660da64412e7'/>\r\n <div style=\"padding:1em;text-align:right;\">\r\n <label style=\"padding-right:1em;\">Handle:\r\n <input style=\"width:12em;\" type=\"text\" class=\"handleBox\"/>\r\n 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<span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>,\r\n \r\n <img style=\"position: relative;top: 5px;\" src=\"//codeforces.org/s/81027/images/flags/24/gb.png\" alt=\"In English\" title=\"In English\"/>\r\n\r\n\r\n\r\n <span style=\"position:absolute;right:0;top:0.05em;margin-right:1em;display:inline;font-size:0.75em;\">\r\n <div style=\"margin-top:0.25em;\">\r\n </div>\r\n </span>\r\n </div>\r\n\r\n <div class=\"content\">\r\n <div class=\"ttypography\"><p>Qualification Round 1</p><p>A <a href=\"/contest/158/problem/A\" title=\"VK Cup 2012 Qualification Round 1\">158A - Next Round</a></p><p>Just sort. Notice 0 in the array.</p><p>B <a href=\"/contest/158/problem/B\" title=\"VK Cup 2012 Qualification Round 1\">158B - Taxi</a></p><p>Choose the 3 and 1 as much as possible. And let 2 combine with themselves. If there are more 1s and 2s, let two 1s combine with 2, and every four 1s take same taxi.</p><p>C <a href=\"/contest/158/problem/C\" title=\"VK Cup 2012 Qualification Round 1\">158C - Cd and pwd commands</a></p><p>Implement with stack. If the string begin with '/', let top = 0, else remain the top; Then process the substring one by one, when meeting ".." , top--; else remain the top;</p><p>D <a href=\"/contest/158/problem/D\" title=\"VK Cup 2012 Qualification Round 1\">158D - Ice Sculptures</a></p><p>The number of new regular polygon's edges must be the factor of the given polygon. Listing all the factors take O(sqrt(n)) time. Then choose the best point take O(n). So the time complexity is O(n*sqrt(n)).</p><p>E <a href=\"/contest/158/problem/E\" title=\"VK Cup 2012 Qualification Round 1\">158E - Phone Talks</a></p><p>It's a classic DP problem. Array dp[i][j] stands for the min rightmost endpoint when choosing at most j segments from the first i segments . dp[i][j] =dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]). When the dp array is completed , find the max value of left[i+1]-dp[i][k] and rightmost point — dp[n][k]. Totally take O(n*n).</p><p>Qualification Round 2</p><p>A <a href=\"/contest/159/problem/A\" title=\"VK Cup 2012 Qualification Round 2\">159A - Friends or Not</a></p><p>Compare every two records and find the right friends. Give every name a unique number so as to avoid counting same friend twice. If a and b is friends, let friend[a][b] = true.</p><p>B <a href=\"/contest/159/problem/B\" title=\"VK Cup 2012 Qualification Round 2\">159B - Matchmaker</a></p><p>Establish two hash tables counting the number of the size (say 2) exiting in set makers and set caps. Obviously the sum of min number of every size in two sets is the first answer. Similarly establish two hash tables in order to count the number of the same size and same color. The hash function can be hash(color, size) = color*1000+size.</p><p>C <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a></p><p>Because the length of string is at most 100*2000, so we can build 26 line-segment-trees to count the 26 Latin letters. The way to build tree and find the position of K-th letter is quite simple if you under stand line-segment-tree :)</p><p>D <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a></p><p>A dp method is really great~ , sum[i] stands for the number of palindrome string in the first i letters. palindrome[i][j] judges weather the substring i...j is a palindrome string. dp[i] is the answer for the first i letters. dp[i] = dp[i-1]+Sum( palindrome[j][i]*sum[j-1] ) for all j<=i && j>0 . sum[i] = sum[i-1]+Sum(palindrome[j][i]) for all j<=i.</p><p>E <a href=\"/contest/159/problem/E\" title=\"VK Cup 2012 Qualification Round 2\">159E - Zebra Tower</a></p><p>sort the array with compare condition (cube[i].color < cube[j].color ||(cube[i].color==cube[j].color && cube[i].size>cube[j].size)). Then for the first i cubes , there is a array Max_cube, Max_cube[j] records the max sum of j cubes' size with same color. To the cube i+1, if it's the k-th largest size of its color. Compare the answer with cube[i+1].size + max(Max_cube[k],Max_cube[k+1],Max_cube[k-1]). The time complexity is O(n*logn).</p><p>Forgive my poor English :)</p><p>gl and hf tonight!</p></div>\r\n\r\n </div>\r\n\r\n\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/158\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 1</a> </span>\r\n </div>\r\n <div style=\"font-size: 1.1rem;line-height: 1.1rem;padding-bottom: 0.5em;\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/paperclip-16x16.png\" style=\"vertical-align: middle;\"/> <span style=\"padding: 0 0.35em;\">Tutorial of <a href=\"/contest/159\" class=\"notice\" style=\"text-decoration: none;\">VK Cup 2012 Qualification Round 2</a> </span>\r\n </div>\r\n \r\n <script type=\"text/javascript\">\n $(document).ready(function () {\n $(\".delete-resource-link-7269-4103\").click(function() {\n var that = this;\n Codeforces.confirm(\"Are you sure you want to detach a contest?\", function () {\n $.post(\"/data/blogAndContest\", {\n action: \"detachBlogFromContest\",\n blogId: \"7269\",\n blogEntryId: \"4089\",\n contestId: $(that).attr(\"data-contestId\"),\n resourceIds: $(that).attr(\"data-resourceIds\")\n }, function(json) { \n Codeforces.reloadAndShowMessageOrShowError(json, \"Contest detached\");\n });\n }, function () {}, \"Yes\", \"No\");\n });\n });\n</script>\r\n \r\n\r\n <div style=\"font-size: 1.1rem;line-height: 11px;\">\r\n <img style=\"vertical-align: middle;\" src=\"//codeforces.org/s/81027/images/blog/tags.png\" title=\"Tags\" alt=\"Tags\"/>\r\n <span style=\"padding: 0 0.35em;\">\r\n <a href=\"/search?query=vk+cup\" class=\"tag notice\" style=\"text-decoration: none;\">vk cup</a>\r\n </span>\r\n </div>\r\n\r\n\n <div class=\"roundbox meta borderTopRound borderBottomRound\" style=\"\">\n <div class=\"left-meta\">\r\n <ul>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-up-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/voteup.png\"\n alt=\"Vote: I like it\" title=\"Vote: I like it\"\n /></a>\n\n\n</li>\r\n <li style=\"line-height: 1.6em;\">\n\n \n <span title=\"Topic rating\" style='font-size:larger;position:relative;bottom:1px;font-weight:bold;color:green'>+39</span>\n \n</li>\r\n <li style=\"line-height: 1.6em;\"> <a href=\"#\" class=\"topic-vote-down-4103\"><img style=\"vertical-align:middle;position:relative;top:-0.2em\" src=\"//codeforces.org/s/81027/images/actions/votedown.png\"\n alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"\n /></a>\n\n\n</li>\r\n </ul>\r\n </div>\r\n\r\n\r\n <span style=\"position: relative; line-height: 1.65em; top: 0.75rem; left: 0.8em;\">\r\n </span>\r\n\r\n <div class=\"right-meta\">\r\n <ul>\r\n <li> <a href=\"/profile/hanfei19910905\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/user_16x16.png\"\n alt=\"Author\" title=\"Author\"\n /></a>\n\n\n <a href=\"/profile/hanfei19910905\">\n hanfei19910905\n </a>\n</li>\r\n <li> <img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/date_16x16.png\"\n alt=\"Publication date\" title=\"Publication date\"\n />\n\n\n \n <span class=\"format-humantime\" title=\"Mar/11/2012 16:16\">12 years ago</span>\n \n</li>\r\n <li> <a href=\"/blog/entry/4089#comments\"><img style=\"vertical-align:middle;position:relative;top:-1px\" src=\"//codeforces.org/s/81027/images/blog/comments_16x16.png\"\n alt=\"Comments\" title=\"Comments\"\n /></a>\n\n\n <a href=\"/blog/entry/4089#comments\">\n 60\n </a>\n</li>\r\n </ul>\r\n </div>\r\n\r\n <br style=\"clear:both;\"/>\r\n </div>\n\r\n\r\n<style type=\"text/css\">\r\n .comments .title {\r\n float: left;\r\n }\r\n\r\n .comments .comments-actions-div {\r\n float: right;\r\n margin-top: 3rem;\r\n margin-right: 0.5em;\r\n }\r\n\r\n .comments .comments-actions-div .separator {\r\n margin: 0 1rem;\r\n }\r\n\r\n .comments label.show-archived {\r\n }\r\n\r\n .comments label.show-archived, .comments label.show-archived * {\r\n font-size: 1.4rem !important;\r\n color: black !important;\r\n /*position: relative !important;*/\r\n /*bottom: 0.4rem !important;*/\r\n }\r\n\r\n .comments label.show-archived input {\r\n height: 1.4rem !important;\r\n width: 1.4rem !important;\r\n position: relative;\r\n top: 0.25rem;\r\n }\r\n\r\n .new-root-comment {\r\n font-size: 1.4rem !important;\r\n }\r\n</style>\r\n\r\n <div class=\"comments\" commentableId=\"4113\">\r\n <div style=\"display: flow-root\">\r\n <div class=\"title\">\r\n <img src=\"//codeforces.org/s/81027/images/icons/comments-48x48.png\" alt=\"Comments\" title=\"Comments\"\r\n style=\"position:relative;top:0.6em;\"/>\r\n <a name=\"comments\">Comments (27)</a>\r\n\r\n </div>\r\n <div class=\"comments-actions-div\">\r\n <label class=\"show-archived\">\r\n <input type=\"checkbox\"\r\n class=\"show-archived-checkbox\" \n/>\r\n Show archived\r\n </label>\r\n <span class=\"separator\">|</span>\r\n <a href=\"#\" class=\"new-root-comment\"\r\n >Write comment?</a>\r\n </div>\r\n </div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83075\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/AlGebr\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/41684/avatar/3ed8d16ad0922efd.jpg'/> </a>\n <div><a href=\"/profile/AlGebr\" title=\"Expert AlGebr\" class=\"rated-user user-blue\">AlGebr</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 16:54\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83075\" href=\"?#comment-83075\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83075\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"3\"\r\n data-commentUserId=\"41684\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+3</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83075\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In <a href=\"/contest/159/problem/D\" title=\"VK Cup 2012 Qualification Round 2\">159D - Palindrome pairs</a>, if you know a method to find all the subpalindromes fast, you can get a better than O(L^2) solution:</p> <ol> <li><p>Make two Segment Trees for counting the starts and the ends of palindromes.</p></li> <li><p>If a palindrome(for example, odd) has center at position K and maximum length 2 * D + 1, then: 1 palindrome starts in K and ends in K, 1 starts in K — 1 and ends in K + 1, ..., last starts in K — D and ends in K + D. So, for adding their ends and starts in O(log L), we use segment updating.</p></li> <li><p>What is the answer on the task? It's just a sum: for all K = 1, 2.., L — 1 we multiply the number of palindromes, that ended in K(exactly), and the number of palindromes starting later, i.e. st[K + 1] + st[K + 2] + ... + st[L]. Each number we can get in O(log L), using ST.</p></li> </ol></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83075 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83075 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83075\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83079\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/11/2012 17:04\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83079\" href=\"?#comment-83079\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83079\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83079\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Yeah, it's a better solution. And it seems that suffix array can work well in finding all palindromes , but i'm not good at it :( .</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83079 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83079 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83079\">\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83550\" commentParentId=\"83075\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/14/2012 16:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83550\" href=\"?#comment-83550\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83075\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83550\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83550\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83550\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>There is O(n) solution. There is way to find palindromes is O(n) using Z-function-like algorithm. And we can to perform all queries to segment trees offline. First preprocess all Add queries for O(n), and then answer all Sum queries.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83550 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83550 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83550\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"390868\" commentParentId=\"83550\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2017 05:37\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-390868\" href=\"?#comment-390868\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83550\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"390868\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-390868\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>can you please explain your approach how this Z-function works here? it will be really helpful !</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-390868 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-390868 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-390868\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391307\" commentParentId=\"390868\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/goo.gl_SsAhv\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/goo.gl_SsAhv\" title=\"Candidate Master goo.gl_SsAhv\" class=\"rated-user user-violet\">goo.gl_SsAhv</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 03:28\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391307\" href=\"?#comment-391307\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-390868\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"391307\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"1\"\r\n data-commentUserId=\"948\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:green;font-weight:bold;\">+1</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391307\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I can't remember what talk about 6 years ago. There is original article in Russian <a href=\"http://e-maxx.ru/algo/palindromes_count\">http://e-maxx.ru/algo/palindromes_count</a> You can translate it using machine translation, but I think this transation isn't good <a href=\"https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url\">https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fe-maxx.ru%2Falgo%2Fpalindromes_count&edit-text=&act=url</a> There was project far transalting site "e-maxx.ru" in english try to google it</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391307 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391307 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391307\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"391330\" commentParentId=\"391307\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/pk842\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/pk842\" title=\"Candidate Master pk842\" class=\"rated-user user-violet\">pk842</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/19/2017 10:01\">6 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-391330\" href=\"?#comment-391330\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-391307\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"391330\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"391330\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"622451\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-391330\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thanks a ton for this !!</p><p>though it make little difference in this problem, but it is good! </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-391330 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-391330 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-391330\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83459\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 00:09\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83459\" href=\"?#comment-83459\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83459\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83459\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83459\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am quite new to sport programming so I have never implemented a segment tree. I heard about it, though, but thought it was complicated. Anyway, I think my solution to <a href=\"/contest/159/problem/C\" title=\"VK Cup 2012 Qualification Round 2\">159C - String Manipulation 1.0</a> is quite neat :)</p><p>In short: binary search in a Fenwick tree.</p><p>Slightly longer: we start out with 26 arrays, all filled with 1's and having a length of k*repeats[c], where repeats is an array containing the number of occurrences of each character in the initial string. Then, we build a Fenwick tree on top of each of these arrays. After that, we start processing the request. For each request p_i, c_i, we perform a binary search in the corresponding Fenwick tree in order to find the leftmost position with p_i 1's before it. Then, we replace the 1 in that position with a 0. Each search takes O(log(k*repeats[c_i])) queries to the Fenwick tree, each being of O(log(k*repeats[c_i])) complexity, which yields O(log^2(k*repeats[c_i])) per each request. The entire complexity of the algorithm is O(n*log^2(k*|s|)).</p><p>After processing all requests, we extract the result by merely moving through the input string k times, each time either printing the corresponding character (if there's a 1 in its array) or omitting it.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83459 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83459 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83459\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"248101\" commentParentId=\"83459\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/radical\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/202716/avatar/b4ddb3c626230b08.jpg'/> </a>\n <div><a href=\"/profile/radical\" title=\"Expert radical\" class=\"rated-user user-blue\">radical</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Aug/26/2015 15:54\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-248101\" href=\"?#comment-248101\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83459\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"248101\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"202716\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-248101\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I also use this method. It really works. This is my code. <a href=\"/contest/159/submission/12708008\" title=\"Submission 12708008 by radical\">12708008</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-248101 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-248101 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-248101\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83484\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/vexorian\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/549/avatar/2235a13a7a204942.jpg'/> </a>\n <div><a href=\"/profile/vexorian\" title=\"Candidate Master vexorian\" class=\"rated-user user-violet\">vexorian</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/13/2012 19:24\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83484\" href=\"?#comment-83484\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83484\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"549\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83484\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I was trying a tree solution for C, but was getting wrong answers and eventually decided to make a solution that supposedly took advantage of the fact that the string is cyclic. Yet in reality, I think it can easily become a solution that needs O(sqrt(|ss|)) time to process each command. (Where ss is s repeated k times) (Currently it is O(|s| + k ). </p><p>There are initially k fragments of the ss string what you could do is for each of the k fragments, ad each letter, know the number of times the letter appears in the fragment and the positions of those appearances.</p><p>Now, in order to delete the P-th instance of a letter in the overall string (ss), you can first do a O(|k|) loop to find the fragment that has the p-th instance (Use the sums for each fragment instead of going through the letters in the fragment manually). After you find the fragment, you can use a O(|s|) loop to naively remove the [p — (sum of the letter counts of previous fragments) ]-th instance of the letter in the fragment.</p><p>This only looks like abusing the format of the string, because you can adapt it to work in O(sqrt(|s|)) time for any string (not just cyclic). So, let's say that ss has |ss| elements, you can always split it into O(sqrt|ss|) fragments of O(sqrt|ss|) letters each. The overall complexity would become O(sqrt|ss|) per step. The constraints make this good enough.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83484 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83484 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83484\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83581\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/D.D.C\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/19304/avatar/c6a41ad077e5fb31.jpg'/> </a>\n <div><a href=\"/profile/D.D.C\" title=\"Specialist D.D.C\" class=\"rated-user user-cyan\">D.D.C</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 04:58\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83581\" href=\"?#comment-83581\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83581\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"19304\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83581\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I am trying understand the 158E Phone calls solution but it seems a little complicated for me. In my little experience with dp I haven't found a problem like this. Could you explain the solution in more detail? Please!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83581 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83581 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83581\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83582\" commentParentId=\"83581\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 08:55\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83582\" href=\"?#comment-83582\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83581\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83582\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83582\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83582\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Suppose we processed the first i calls and j of those were ignored, the best way is to minimize the last minute of conversation (i.e. maximize the length of freetime until the current moment). It's the meaning of dp[i][j]. If you still can't get it, feel free to point out what you are confused :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83582 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83582 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83582\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83584\" commentParentId=\"83582\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 10:12\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83584\" href=\"?#comment-83584\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83582\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"83584\" revisionCount=\"3\" revision=\"3\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">3</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"83584\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83584\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Problem is, topicstarter's formula for dp[i][j] is wrong. It should be:</p><p>dp[i][j] = min(dp[i-1][j-1], max(dp[i-1][j],left[i])+length[i]), not</p><p>dp[i][j] = min(dp[i-1][j], max(dp[i-1][j-1],left[i])+length[i])</p><p>Here is my submission with this solution: <a href=\"/contest/158/submission/1355912\" title=\"Submission 1355912 by Kelang\">1355912</a>.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83584 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83584 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83584\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83604\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/flashmt\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3541/avatar/91a39db4151651f0.jpg'/><img title='Badge of honor for supporting Codeforces on its 10th anniversary' src='//codeforces.org/s/81027/images/if_medal-bronze-blue_46108.png' style='position:absolute;bottom:-4px;right:-6px'/> </a>\n <div><a href=\"/profile/flashmt\" title=\"International Master flashmt\" class=\"rated-user user-orange\">flashmt</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/15/2012 15:48\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83604\" href=\"?#comment-83604\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83604\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3541\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83604\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>In my opinion, understanding its meaning is more important. If you know how it work, it isn't difficult to get the correct formula. </p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83604 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83604 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83604\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"83655\" commentParentId=\"83604\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Kelang\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/Kelang\" title=\"Expert Kelang\" class=\"rated-user user-blue\">Kelang</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/16/2012 18:41\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-83655\" href=\"?#comment-83655\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83604\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"83655\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"47256\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-83655\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>The meaning is pretty straightforward. Suppose that you know, for all previous i's and j's, the least time at which all calls end. You are currently considering whether it is a good idea to add the current call to the ones you omit, or not. This depends on the time all calls are going to end at.</p> <ul> <li><p>If you choose to omit it, you need to look at the time at which i-1 calls ended, and you dropped j-1 of them (because the newly dropped call is going to be the j-th).</p></li> <li><p>Otherwise, you're going to look at the time at which i-1 calls ended, out of which j were dropped (since it is always preferable to drop as many calls as possible). Then, you should find the time at which the i-th call is going to end. Since you already know when i-1 calls ended and when the i-th call is supposed to start, you should find the time at which it actually starts — by merely taking a maximum. After that, you just add its length to the time it starts.</p></li> </ul><p>You are interested in minimizing the time, so you take the minimum.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-83655 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-83655 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-83655\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"84062\" commentParentId=\"83584\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/hanfei19910905\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/21124/avatar/b3328e241bd02ed.jpg'/> </a>\n <div><a href=\"/profile/hanfei19910905\" title=\"Candidate Master hanfei19910905\" class=\"rated-user user-violet\">hanfei19910905</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Mar/18/2012 11:38\">12 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-84062\" href=\"?#comment-84062\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-83584\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"84062\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"21124\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-84062\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>thx for correcting my mistake :)</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-84062 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-84062 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-84062\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"255451\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/alibaba\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/alibaba\" title=\"Expert alibaba\" class=\"rated-user user-blue\">alibaba</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/08/2015 21:24\">8 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-255451\" href=\"?#comment-255451\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"255451\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"97169\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-255451\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>This is not tutorial of VK 2015, can some body remove the tag?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-255451 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-255451 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-255451\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289903\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Guffy\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/402733/avatar/d5e60c3f010be2e1.jpg'/> </a>\n <div><a href=\"/profile/Guffy\" title=\"Pupil Guffy\" class=\"rated-user user-green\">Guffy</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 06:51\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289903\" href=\"?#comment-289903\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"289903\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"289903\" class=\"CommentVoteFrame\"\r\n class=\"negative-comment-vote\"\r\n data-commentRating=\"-15\"\r\n data-commentUserId=\"402733\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-15</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289903\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Thanks for all!</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289903 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289903 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289903\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"289910\" commentParentId=\"289903\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Lelby\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/53077/avatar/5c2a11771c32a648.jpg'/> </a>\n <div><a href=\"/profile/Lelby\" title=\"Candidate Master Lelby\" class=\"rated-user user-violet\">Lelby</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/20/2016 08:58\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-289910\" href=\"?#comment-289910\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-289903\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"289910\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"53077\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-289910\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>You output nothing on this test. What is your question?</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-289910 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-289910 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-289910\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335054\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/fkabir_zisan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/fkabir_zisan\" title=\"Pupil fkabir_zisan\" class=\"rated-user user-green\">fkabir_zisan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:03\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335054\" href=\"?#comment-335054\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"335054\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"335054\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"401942\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335054\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>B taxi. wrong answer on 67. can't even see inputs!</p><p><a href=\"http://ideone.com/cTEsEx\">http://ideone.com/cTEsEx</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335054 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335054 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335054\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"335055\" commentParentId=\"335054\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/shakil.ahamed\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/271742/avatar/78cc93f5250336a3.jpg'/> </a>\n <div><a href=\"/profile/shakil.ahamed\" title=\"Expert shakil.ahamed\" class=\"rated-user user-blue\">shakil.ahamed</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/02/2017 10:07\">7 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-335055\" href=\"?#comment-335055\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-335054\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"335055\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"271742\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-335055\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>Use <a href=\"http://ideone.com\">ideone.com</a> to share code.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-335055 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-335055 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-335055\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"710662\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Qualified\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1437699/avatar/b4adddec9bf8fdc6.jpg'/> </a>\n <div><a href=\"/profile/Qualified\" title=\"Expert Qualified\" class=\"rated-user user-blue\">Qualified</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/16/2020 22:49\">3 years ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-710662\" href=\"?#comment-710662\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"710662\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1437699\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-710662\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I solved <a href=\"https://codeforces.com/contest/159/problem/D\">problem D</a> using <a href=\"https://cp-algorithms.com/string/manacher.html\">Manacher's Algo</a> and prefix sums. <a href=\"/contest/159/submission/95691489\" title=\"Submission 95691489 by Qualified\">95691489</a></p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-710662 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-710662 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-710662\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"985061\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/nk1745\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/2672916/avatar/5e5d210fe24d995c.jpg'/> </a>\n <div><a href=\"/profile/nk1745\" title=\"Newbie nk1745\" class=\"rated-user user-gray\">nk1745</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Dec/26/2022 13:22\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-985061\" href=\"?#comment-985061\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"985061\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"-8\"\r\n data-commentUserId=\"2672916\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">-8</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-985061\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>A 158A — Next Round is there some glitch in the test case no-3. as per question , Contestant who earns a score equal to or greater than the k-th place finisher's score will advance to the next round, as long as the contestant earns a positive score..." — an excerpt from contest rules. But there are not including the equal to case here, this is my code -> #include <bits/stdc++.h> using namespace std;</p><p>int main() { int n, k; cin >> n >> k; int cnt = 0; for (int i = 0; i < n; i++) { int a[100]; cin >> a[i];</p> <pre>if (a[i] > 0 && a[i] >= a[ k - 1])\n cnt++;\n}\ncout << cnt;\nreturn 0;</pre><p>}</p><p>Please ,tell me my fault. Thanks in advance.</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-985061 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-985061 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-985061\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"990904\" commentParentId=\"985061\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/gwinell\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3009480/avatar/dd60c610324b38bd.jpg'/> </a>\n <div><a href=\"/profile/gwinell\" title=\"Newbie gwinell\" class=\"rated-user user-gray\">gwinell</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/10/2023 00:02\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-990904\" href=\"?#comment-990904\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-985061\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"990904\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3009480\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-990904\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>I'm also trying to find my fault, because I have no idea what is the test 3</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-990904 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-990904 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-990904\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"992168\" commentParentId=\"990904\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/khanxbahria\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/no-avatar.jpg'/> </a>\n <div><a href=\"/profile/khanxbahria\" title=\"Newbie khanxbahria\" class=\"rated-user user-gray\">khanxbahria</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jan/13/2023 12:09\">9 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-992168\" href=\"?#comment-992168\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-990904\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"992168\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"2092061\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-992168\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>#include <bits/stdc++.h>\nusing namespace std;\n\nint main(){\n\tint n, k;\n\tcin >> n >> k;\n\tint a[n];\n\tint cnt =0;\n\tfor(int i=0; i<n; i++) cin >> a[i];\n\tfor(int i=0; i<n; i++){\n\t\tif(a[i]> 0 && a[i]>=a[k-1]) cnt++;\n\t\telse break;\n\t}\n\tcout << cnt << endl;\n}\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-992168 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-992168 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-992168\">\r\n <li>\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1019714\" commentParentId=\"992168\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/SaraIschan\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/1943309/avatar/2cf640e883844725.jpg'/> </a>\n <div><a href=\"/profile/SaraIschan\" title=\"Newbie SaraIschan\" class=\"rated-user user-gray\">SaraIschan</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Apr/04/2023 19:54\">6 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1019714\" href=\"?#comment-1019714\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\"><a title=\"Parent comment\" href=\"#comment-992168\" style=\"font-size:1.2em;\">^</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1019714\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"1943309\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1019714\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>delete "else break"</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1019714 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1019714 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1019714\">\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n</li>\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1052278\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/Morsalin_Islam\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3190789/avatar/25e28198972ea31c.jpg'/> </a>\n <div><a href=\"/profile/Morsalin_Islam\" title=\"Newbie Morsalin_Islam\" class=\"rated-user user-gray\">Morsalin_Islam</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Jul/28/2023 04:55\">2 months ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1052278\" href=\"?#comment-1052278\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n <span style=\"\" commentId=\"1052278\" revisionCount=\"2\" revision=\"2\">\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;color:#bebebe;\" class=\"leftRevision\">←</a>\r\n Rev. <span class=\"revision\">2</span>\r\n <a href=\"#\" style=\"text-decoration:none;font-size:1.4rem;visibility:hidden;color:#bebebe;\" class=\"rightRevision\">→</a>\r\n </span>\r\n \r\n\r\n<span commentid=\"1052278\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3190789\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1052278\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><pre><code>// This is a easiest way to solve this problem.\n// Time complexity: O(N)\n// Space complexity: O(N)\n</code></pre> <pre><code>include<bits/stdc++.h>\nusing namespace std;\nint main()\n{\n int n, k, ans = 0;\n cin >> n >>k; int arr[n];// without arr array time and space complexity O(1)\n for(int i = 0; i < n; i++) cin >> arr[i];// Time and Space complexity O(N)\n for(int i = 0; i < n; i++)// Time complexity O(N)\n {\n if(arr[i] > 0 && arr[i] >= arr[k - 1])ans ++;//if arr(ith index) >0 and arr(ith index) >= arr(k - 1 th index) ans will be increase by 1\n }\n cout<<ans;\n // Total time complexity + Space complexity of this program is O(N)[always calculate from worse case]\n return 0;\n</code></pre></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1052278 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1052278 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1052278\">\r\n </ul>\r\n</div>\r\n\r\n<div class=\"comment\">\r\n <table class=\"comment-table\"\r\n commentId=\"1074727\" commentParentId=\"-1\">\r\n <tr>\r\n <td class=\"left\">\r\n <div style=\"position: absolute; left: 0;\" class=\"comment-indent-holder\">\r\n <div class=\"comment-no-indent\">\r\n <span>»</span>\r\n </div>\r\n </div>\r\n <div class=\"avatar\">\n <a href=\"/profile/bonna_nkstld\" style=\"position: relative;\">\n<img src='https://userpic.codeforces.org/3092579/avatar/67afbac9270d0ea9.jpg'/> </a>\n <div><a href=\"/profile/bonna_nkstld\" title=\"Unrated, bonna_nkstld\" class=\"rated-user user-black\">bonna_nkstld</a></div>\n </div>\n </td>\r\n <td class=\"right\">\r\n <div class=\"info\">\r\n \r\n <span class=\"item\"><span class=\"format-humantime\" title=\"Oct/07/2023 11:12\">11 hours ago</span>,</span>\r\n <span class=\"item\"><a title=\"Link to comment\" name=\"comment-1074727\" href=\"?#comment-1074727\" style=\"font-size:1.2em;\">#</a></span>\r\n <span class=\"item\">|</span>\r\n <span style=\"position: relative; top: 2px;\">\r\n</span>\r\n <div style=\"position:absolute;right:0;top:0;\">\r\n \r\n\r\n<span commentid=\"1074727\" class=\"CommentVoteFrame\"\r\n data-commentRating=\"0\"\r\n data-commentUserId=\"3092579\"\r\n style=\"position:relative;\"\r\n>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"1\" dd=\"x\"><img style=\"position:relative;top:3px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-voteup-blue.png\" alt=\"Vote: I like it\" title=\"Vote: I like it\"/></a>\r\n<span class=\"commentRating\"><span style=\"color:gray;font-weight:bold;\">0</span></span>\r\n<a href=\"#\" class=\"vote-for-comment\" voteDirection=\"-1\" dd=\"y\"><img style=\"position:relative;top:2px;opacity:0.35;\" src=\"//codeforces.org/s/81027/images/actions/comment-votedown-blue.png\" alt=\"Vote: I do not like it\" title=\"Vote: I do not like it\"/></a>\r\n\n<style data-nocturne=\"true\" type=\"text/css\">\n.ComplaintFrame {\n display: inline-block;\n position: absolute;\n top: 0;\n right: -1.4em;\n}\n.ComplaintFrame a {\n text-decoration: none;\n color: #ff8c00;\n opacity: 0.5;\n}\n.ComplaintFrame a:hover {\n opacity: 1;\n}\n._ComplaintFrame_popup p,\n._ComplaintFrame_popup button {\n margin-top: 1rem;\n}\n._ComplaintFrame_popup input[type=submit] {\n padding: 0.25rem 2rem;\n}\n._ComplaintFrame_popup ul {\n margin-top: 1em !important;\n margin-bottom: 1em !important;\n}\n</style>\n\n\n<script data-nocturne=\"true\"> $(function () {\n $(\".ComplaintFrame a\").click(function () {\n const $complaintFrame = $(this).closest(\".ComplaintFrame\");\n const targetId = $complaintFrame.attr(\"data-targetId\");\n const targetClass = $complaintFrame.attr(\"data-targetClass\");\n\n Codeforces.facebox(\"._ComplaintFrame_popup\", \"//codeforces.org/s/81027\");\n\n $.post(\"/data/complaint\", {\n action: \"findComplaintReasons\",\n targetClass: $complaintFrame.attr(\"data-targetClass\"),\n targetId: $complaintFrame.attr(\"data-targetId\")\n }, function (response) {\n if (response.success === \"true\") {\n const complaintReasons = response.complaintReasons;\n const complaint = response.complaint;\n\n const $popup = $(\"#facebox ._ComplaintFrame_popup\");\n for (const complaintReason of complaintReasons) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", complaintReason.id);\n $li.find(\"span\")\n .html(getLocalizedName(complaintReason)\n + \" <i class=\\\"icon-question-sign clickable-title\\\" title=\\\"\"\n + getLocalizedDescription(complaintReason)\n + \"\\\"></i>\")\n .attr(\"title\", getLocalizedDescription(complaintReason));\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n if (complaint && complaint.complaintReasonId === complaintReason.id) {\n $li.find(\"input[name=complaintReasonId]\").attr(\"checked\", \"checked\");\n }\n $li.find(\".clickable-title\").click(function () {\n alert(getLocalizedDescription(complaintReason));\n return false;\n }).css(\"position\", \"relative\").css(\"bottom\", \"1px\").css(\"font-size\", \"12px\");\n }\n\n if (complaint) {\n let $li = $(\"#facebox ._ComplaintFrame_complaintReasonItemProto li\").clone();\n $li.find(\"input[name=complaintReasonId]\").attr(\"value\", 0);\n $li.find(\"span\").html(\"Delete complaint\");\n $li.show();\n $li.appendTo($popup.find(\"ul\"));\n }\n\n $popup.find(\"._ComplaintFrame_submitForm\").submit(function () {\n const complaintReasonId = $popup.find(\"input[name=complaintReasonId]:checked\").val();\n if (complaintReasonId === undefined) {\n alert(\"Please select complaint reason\");\n return false;\n }\n\n $.post(\"/data/complaint\", {\n action: \"newComplaint\",\n targetClass: targetClass,\n targetId: targetId,\n complaintReasonId: complaintReasonId\n }, function (response) {\n if (response.success === \"true\") {\n Codeforces.showMessage(\"Complaint has been created\");\n $.facebox.close();\n }\n }, \"json\");\n\n return false;\n });\n }\n }, \"json\");\n\n return false;\n });\n}); </script>\n\n</span>\r\n </div>\r\n </div>\r\n <div class=\"comment-content comment-content-1074727\">\r\n <div class=\"moveup\">\r\n <div class=\"ttypography\"><p>On test case 37 the answer's shown as 3 . If n=3 and the numbers of students in each group are about 3 3 2 then it should need 2 cars .why the answer is 3????????? maximum students in a group are 4;</p></div>\r\n </div>\r\n </div>\r\n <div class=\"reply info\">\r\n <a class=\"comment-1074727 en false\" href=\"#\" style=\"text-decoration: none;\"><span class=\"arrow\">→</span></a>\r\n <a class=\"comment-1074727 en false\" href=\"#\">Reply</a>\r\n </div>\r\n </td>\r\n </tr>\r\n </table>\r\n <ul class=\"comment-children comment-1074727\">\r\n </ul>\r\n</div>\r\n <br/>\r\n\r\n<div id=\"editBox-4113\" style=\"width:50em;display:none;\">\r\n <div class=\"previewBody\" style=\"border: 1px solid #d4d4d4; margin-bottom: 0.5em; padding: 0.25em; display:none;\"> </div>\r\n <div style=\"width: 1px\"> </div>\r\n <div class=\"commentLocale\" style=\"position: relative; top: 0.5em;left:4px;display: none;\">\r\n <input type=\"radio\" name=\"locale\" value=\"en\"><span style=\"font-size: 1.2rem;position: relative; bottom: 3px;\">In 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{document.onreadystatechange = prev;handler();}};}})();</script></body>\n</html>\n"}}},{"rowIdx":788,"cells":{"problem_id":{"kind":"string","value":"160A"},"contest":{"kind":"string","value":"160"},"problem":{"kind":"string","value":"A"},"lang":{"kind":"string","value":"en"},"problem_title":{"kind":"string","value":"A. Twins"},"problem_statement":{"kind":"string","value":"<div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Twins</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Imagine that you have a twin brother or sister. Having another person that looks exactly like you seems very unusual. It's hard to say if having something of an alter ego is good or bad. And if you do have a twin, then you very well know what it's like.</p><p>Now let's imagine a typical morning in your family. You haven't woken up yet, and Mom is already going to work. She has been so hasty that she has nearly forgotten to leave the two of her darling children some money to buy lunches in the school cafeteria. She fished in the purse and found some number of coins, or to be exact, <span class=\"tex-span\"><i>n</i></span> coins of arbitrary values <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub>, <i>a</i><sub class=\"lower-index\">2</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i></sub></span>. But as Mom was running out of time, she didn't split the coins for you two. So she scribbled a note asking you to split the money equally.</p><p>As you woke up, you found Mom's coins and read her note. \"But why split the money equally?\" — you thought. After all, your twin is sleeping and he won't know anything. So you decided to act like that: pick for yourself some subset of coins so that the sum of values of your coins is <span class=\"tex-font-style-bf\">strictly larger</span> than the sum of values of the remaining coins that your twin will have. However, you correctly thought that if you take too many coins, the twin will suspect the deception. So, you've decided to stick to the following strategy to avoid suspicions: you take the <span class=\"tex-font-style-bf\">minimum number of coins</span>, whose sum of values is strictly more than the sum of values of the remaining coins. On this basis, determine what <span class=\"tex-font-style-bf\">minimum</span> number of coins you need to take to divide them in the described manner.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>) — the number of coins. The second line contains a sequence of <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">2</sub></span>, ..., <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the coins' values. All numbers are separated with spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the single line print the single number — the minimum needed number of coins.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br/>3 3<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br/>2 1 2<br/></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br/></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you will have to take <span class=\"tex-span\">2</span> coins (you and your twin have sums equal to <span class=\"tex-span\">6, 0</span> correspondingly). If you take <span class=\"tex-span\">1</span> coin, you get sums <span class=\"tex-span\">3, 3</span>. If you take <span class=\"tex-span\">0</span> coins, you get sums <span class=\"tex-span\">0, 6</span>. Those variants do not satisfy you as your sum should be strictly more that your twins' sum.</p><p>In the second sample one coin isn't enough for us, too. You can pick coins with values <span class=\"tex-span\">1, 2</span> or <span class=\"tex-span\">2, 2</span>. 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class=\"ttypography\"><div class=\"problem-statement\"><div class=\"header\"><div class=\"title\">A. Twins</div><div class=\"time-limit\"><div class=\"property-title\">time limit per test</div>2 seconds</div><div class=\"memory-limit\"><div class=\"property-title\">memory limit per test</div>256 megabytes</div><div class=\"input-file\"><div class=\"property-title\">input</div>standard input</div><div class=\"output-file\"><div class=\"property-title\">output</div>standard output</div></div><div><p>Imagine that you have a twin brother or sister. Having another person that looks exactly like you seems very unusual. It's hard to say if having something of an alter ego is good or bad. And if you do have a twin, then you very well know what it's like.</p><p>Now let's imagine a typical morning in your family. You haven't woken up yet, and Mom is already going to work. She has been so hasty that she has nearly forgotten to leave the two of her darling children some money to buy lunches in the school cafeteria. She fished in the purse and found some number of coins, or to be exact, <span class=\"tex-span\"><i>n</i></span> coins of arbitrary values <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub>, <i>a</i><sub class=\"lower-index\">2</sub>, ..., <i>a</i><sub class=\"lower-index\"><i>n</i></sub></span>. But as Mom was running out of time, she didn't split the coins for you two. So she scribbled a note asking you to split the money equally.</p><p>As you woke up, you found Mom's coins and read her note. "But why split the money equally?" — you thought. After all, your twin is sleeping and he won't know anything. So you decided to act like that: pick for yourself some subset of coins so that the sum of values of your coins is <span class=\"tex-font-style-bf\">strictly larger</span> than the sum of values of the remaining coins that your twin will have. However, you correctly thought that if you take too many coins, the twin will suspect the deception. So, you've decided to stick to the following strategy to avoid suspicions: you take the <span class=\"tex-font-style-bf\">minimum number of coins</span>, whose sum of values is strictly more than the sum of values of the remaining coins. On this basis, determine what <span class=\"tex-font-style-bf\">minimum</span> number of coins you need to take to divide them in the described manner.</p></div><div class=\"input-specification\"><div class=\"section-title\">Input</div><p>The first line contains integer <span class=\"tex-span\"><i>n</i></span> (<span class=\"tex-span\">1 ≤ <i>n</i> ≤ 100</span>) — the number of coins. The second line contains a sequence of <span class=\"tex-span\"><i>n</i></span> integers <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">1</sub></span>, <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\">2</sub></span>, ..., <span class=\"tex-span\"><i>a</i><sub class=\"lower-index\"><i>n</i></sub></span> (<span class=\"tex-span\">1 ≤ <i>a</i><sub class=\"lower-index\"><i>i</i></sub> ≤ 100</span>) — the coins' values. All numbers are separated with spaces.</p></div><div class=\"output-specification\"><div class=\"section-title\">Output</div><p>In the single line print the single number — the minimum needed number of coins.</p></div><div class=\"sample-tests\"><div class=\"section-title\">Examples</div><div class=\"sample-test\"><div class=\"input\"><div class=\"title\">Input</div><pre>2<br />3 3<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div><div class=\"input\"><div class=\"title\">Input</div><pre>3<br />2 1 2<br /></pre></div><div class=\"output\"><div class=\"title\">Output</div><pre>2<br /></pre></div></div></div><div class=\"note\"><div class=\"section-title\">Note</div><p>In the first sample you will have to take <span class=\"tex-span\">2</span> coins (you and your twin have sums equal to <span class=\"tex-span\">6, 0</span> correspondingly). If you take <span class=\"tex-span\">1</span> coin, you get sums <span class=\"tex-span\">3, 3</span>. If you take <span class=\"tex-span\">0</span> coins, you get sums <span class=\"tex-span\">0, 6</span>. Those variants do not satisfy you as your sum should be strictly more that your twins' sum.</p><p>In the second sample one coin isn't enough for us, too. You can pick coins with values <span class=\"tex-span\">1, 2</span> or <span class=\"tex-span\">2, 2</span>. 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