#include <bits/stdc++.h>   using namespace std;   inline long long int c(long long int n, long long int i) {     if (i == 0)       return 1;     else if (i == 1)       return n;     else if (i == 2)       return (n * (n - 1)) / 2;     else if (i == 3)       return (n * (n - 1) * (n - 2)) / 6;     else if (i == 4)       return (n * (n - 1) * (n - 2) * (n - 3)) / 24;   }   int main() {     long long int d[5];     d[0] = 1;     d[1] = 0;     d[2] = 1;     d[3] = 2;     d[4] = 9;     long long int n, k;     cin >> n >> k;     long long int ans = 0;     for (long long int i = 0; i <= k; i++) ans += d[i] * c(n, i);     cout << ans;     return 0;   }   