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| #include <bits/stdc++.h> |
| using namespace std; |
|
|
| #define ll long long |
| #define ull unsigned long long |
| #define dd double |
| #define ld long double |
| #define sl(n) scanf("%lld", &n) |
| #define si(n) scanf("%d", &n) |
| #define sd(n) scanf("%lf", &n) |
| #define pll pair <ll, ll> |
| #define pii pair <int, int> |
| #define mp make_pair |
| #define pb push_back |
| #define all(v) v.begin(), v.end() |
| #define inf (1LL << 62) |
| #define loop(i, start, stop, inc) for(ll i = start; i <= stop; i += inc) |
| #define for1(i, stop) for(ll i = 1; i <= stop; ++i) |
| #define for0(i, stop) for(ll i = 0; i < stop; ++i) |
| #define rep1(i, start) for(ll i = start; i >= 1; --i) |
| #define rep0(i, start) for(ll i = (start-1); i >= 0; --i) |
| #define ms(n, i) memset(n, i, sizeof(n)) |
| #define casep(n) printf("Case %lld:", ++n) |
| #define pn printf("\n") |
| #define pf printf |
| #define EL '\n' |
| #define fastio std::ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); |
|
|
| const ll sz = 5e4 + 10; |
|
|
| pii ara[sz], lst[sz]; |
| ll pnt[sz], dp[sz]; |
|
|
| struct Line { |
| ll m, c; |
| } tree[4*sz]; |
|
|
| bool exist[4*sz]; |
|
|
| inline ll f(Line &line, ll x) { |
| return line.m*x + line.c; |
| } |
|
|
| void add(ll lo, ll hi, Line line, ll node) |
| { |
| exist[node] = 1; |
|
|
| if(lo == hi) { |
| if(f(line, pnt[lo]) < f(tree[node], pnt[lo])) |
| tree[node] = line; |
| return; |
| } |
|
|
| ll mid = lo+hi >> 1; |
|
|
| bool l = f(line, pnt[lo]) < f(tree[node], pnt[lo]); |
| bool m = f(line, pnt[mid]) < f(tree[node], pnt[mid]); |
|
|
| if(m) swap(tree[node], line); |
|
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| if(l != m) add(lo, mid, line, node<<1); |
| else add(mid +1, hi, line, node<<1|1); |
| } |
|
|
| ll query(ll lo, ll hi, ll idx, ll node) |
| { |
| if(lo == hi) |
| return f(tree[node], pnt[idx]); |
|
|
| ll mid = lo+hi >> 1, ret = f(tree[node], pnt[idx]); |
|
|
| if(idx <= mid && exist[node<<1]) ret = min(ret, query(lo, mid, idx, node<<1)); |
| else if(idx > mid && exist[node<<1|1]) ret = min(ret, query(mid+1, hi, idx, node<<1|1)); |
|
|
| return ret; |
| } |
|
|
| int main() |
| { |
| ll n; |
| cin >> n; |
|
|
| for1(i, n) { |
| si(ara[i].first), si(ara[i].second); |
| } |
| sort(ara+1, ara+n+1); |
|
|
| ll mxw = 0, idx = 0; |
| rep1(i, n) { |
| if(ara[i].second > mxw) |
| lst[++idx] = ara[i]; |
|
|
| mxw = max(mxw, (ll)ara[i].second); |
| } |
| reverse(lst+1, lst+idx+1); |
|
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| for1(i, idx) pnt[i] = lst[i].first; |
| for0(i, 4*sz) tree[i] = {0, inf}; |
|
|
| for1(i, idx) { |
|
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| add(1, idx, {lst[i].second, dp[i-1]}, 1); |
|
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| dp[i] = query(1, idx, i, 1); |
| } |
|
|
| cout << dp[idx] << EL; |
|
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| return 0; |
|
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