func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double pi = 3.1415926535897932384626433832795l;   template <typename T>   inline auto sqr(T x) -> decltype(x * x) {     return x * x;   }   template <typename T1, typename T2>   inline bool umx(T1& a, T2 b) {     if (a < b) {       a = b;       return 1;     }     return 0;   }   template <typename T1, typename T2>   inline bool umn(T1& a, T2 b) {     if (b < a) {       a = b;       return 1;     }     return 0;   }   struct Input {     int n, k;     bool read() {       if (!(cin >> n >> k)) {         return false;       }       return true;     }     void init(const Input& input) { *this = input; }   };   struct Data : Input {     long long ans;     void write() { cout << ans <<   n ; }     virtual void solve() {}     virtual void clear() { *this = Data(); }   };   struct Solution : Data {     void solve() {       ans = 0;       while (n > 1 && k > 0) {         ans += 2 * (n - 1) - 1;         n -= 2;         --k;       }     }     void clear() { *this = Solution(); }   };   Solution sol;   int main() {     cout.setf(ios::showpoint | ios::fixed);     cout.precision(20);     sol.read();     sol.solve();     sol.write();     return 0;   }   