func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int c, d, n, m, k, needed;     cin >> c >> d >> n >> m >> k;     needed = n * m - k;     cout << ((needed <= 0)                  ? 0                  : min(needed * d, min(needed / n * c + needed % n * d,                                        (int)(ceil((double)needed / n) * c))));     return 0;   }   