func_code_string: #include <bits/stdc++.h>   using namespace std;   long long fast_power(long long x, long long y) {     if (y == 0) return 1;     long long temp = fast_power(x, y / 2);     temp = ((temp % 1000000007) * (temp % 1000000007)) % 1000000007;     if (y % 2 != 0) temp = ((temp % 1000000007) * (x % 1000000007)) % 1000000007;     return temp;   }   long long f[1000001];   long long inv[1000001];   long long ncr(long long n, long long r) {     return ((((f[n] % 1000000007) * (inv[n - r] % 1000000007)) % 1000000007) *             inv[r]) %            1000000007;   }   long long nCr(long long n, long long r) {     long long f = 1;     long long x = 1;     for (long long i = n; i > n - r; i--) {       f *= i;       f /= x++;     }     return f;   }   long long npr(long long n, long long r) {     return (f[n] % 1000000007 * inv[n - r] % 1000000007) % 1000000007;   }   int main() {     long long n, r, t;     cin >> n >> r >> t;     f[0] = 1;     inv[0] = 1;     for (long long i = 1; i <= n; i++) {       f[i] = (f[i - 1] * i) % 1000000007;       inv[i] = fast_power(f[i], 1000000007 - 2);     }     long long sum = 0;     if (n >= 4)       for (long long i = 4; i < t; i++) {         if (t - i <= r) sum += nCr(n, i) * nCr(r, t - i);       }     cout << sum <<   n ;     return 0;   }   