func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int mohin, a, b, c;     cin >> a >> b >> c;     mohin = 0;     for (int i = 1; i <= c; i++) {       mohin += 2 * ((a - 4 * (i - 1)) + (b - 4 * (i - 1))) - 4;     }     cout << mohin << endl;     return 0;   }   