func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int x;   int dfs(int xx, int yy, int cc) {     if (cc == 0) {       if (xx == 1 || yy == 1) {         int tt = xx * yy;         if (tt % 2 == 0)           return tt / 2;         else           return tt / 2 + 1;       } else         return ((xx + yy) * 2 - 4) / 2;     }     if (xx <= 2 || yy <= 2) {       if (cc >= 1) return 0;       int k = xx * yy;       if (k % 2 == 0) return k / 2;       return k / 2 + 1;     }     int g = dfs(xx - 2, yy - 2, cc - 1);     return g;   }   int main() {     while (cin >> n >> m >> x) {       int t = dfs(n, m, x - 1);       cout << t << endl;     }   }   