func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(0);     long long n, k, ans = 0;     cin >> n >> k;     if (k >= n / 2)       ans = (n * (n - 1)) / 2;     else {       ans = (n * (n - 1)) / 2 - (((n - k) * (n - k - 1)) / 2) + k * (n - 2 * k) +             (k * (k - 1)) / 2;     }     cout << ans << endl;   }   