func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1000000007;   int n, m;   int popCount(int x) {     int count = 0;     while (x) {       ++count;       x &= x - 1;     }     return count;   }   inline bool Okay(int x) { return (((1 << m) - 1) & x) == ((1 << m) - 1); }   int main() {     ios::sync_with_stdio(false);     cin >> n >> m;     if (n < m) swap(n, m);     int*** Arr = new int**[n + 1];     for (int i = 0; i <= n; ++i) {       Arr[i] = new int*[1 << m];       for (int j = 0; j < (1 << m); ++j) {         Arr[i][j] = new int[1 << m];         for (int k = 0; k < (1 << m); ++k) {           Arr[i][j][k] = 100000000;         }       }     }     Arr[0][(1 << m) - 1][0] = 0;     for (int i = 0; i < n; ++i) {       for (int j = 0; j < (1 << m); ++j) {         for (int k = 0; k < (1 << m); ++k) {           for (int t = 0; t < (1 << m); ++t) {             if (Okay(j | k | t | (k >> 1) | (k << 1)))               Arr[i + 1][k][t] =                   min(Arr[i + 1][k][t], Arr[i][j][k] + popCount(t));           }         }       }     }     int _ans = 100000;     for (int k = 0; k < (1 << m); ++k) {       for (int t = 0; t < (1 << m); ++t) {         if (Okay(k | t | (t << 1) | (t >> 1))) _ans = min(_ans, Arr[n][k][t]);       }     }     cout << n * m - _ans;     return 0;   }   