int modular_power(int base, int exponent, int modulus) ; int binomial_digit_mod_prime(int upper, int lower, int prime) { if (lower > upper) { return 0; } if (lower > upper - lower) { lower = upper - lower; } int numerator = 1; int denominator = 1; for (int i = 1; i <= lower; ++i) { int factor = upper - lower + i; long long numerator_product = (long long)numerator * factor; long long denominator_product = (long long)denominator * i; numerator = (int)(numerator_product % prime); denominator = (int)(denominator_product % prime); } int inverse = modular_power(denominator, prime - 2, prime); long long answer = (long long)numerator * inverse; return (int)(answer % prime); } int lucas_theorem(int n, int m, int prime) { int upper = n + m; int lower = n; int result = 1; while (upper > 0 || lower > 0) { int upper_digit = upper % prime; int lower_digit = lower % prime; if (lower_digit > upper_digit) { return 0; } int digit_binomial = binomial_digit_mod_prime(upper_digit, lower_digit, prime); long long product = (long long)result * digit_binomial; result = (int)(product % prime); upper /= prime; lower /= prime; } return result; }