func_code_string: #include <bits/stdc++.h>   using namespace std;   long long C(long long n, long long m) {     long long res = 1;     for (long long i = n; i > n - m; i--) res *= i;     for (long long i = m; i >= 1; i--) res /= i;     return res;   }   int main() {     ios::sync_with_stdio(0), cin.tie(0);     long long n, k, res = 1;     cin >> n >> k;     if (k >= 2) res += C(n, 2);     if (k >= 3) res += C(n, 3) * 2;     if (k >= 4) res += C(n, 4) * 9;     cout << res << endl;     return 0;   }   