func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 500 + 5;   char mp[maxn][maxn];   int main() {     int n, m;     cin >> n >> m;     for (int i = 0; i < n; i++)       for (int j = 0; j < m; j++) scanf(  %c , &mp[i][j]);     int x1, y1, x2, y2;     for (int i = 0; i < n; i++) {       bool bb = false;       for (int j = 0; j < m; j++)         if (mp[i][j] ==  X ) {           x1 = i;           y1 = j;           bb = true;           break;         }       if (bb) break;     }     for (int i = n - 1; i >= 0; i--) {       bool bb = false;       for (int j = m - 1; j >= 0; j--) {         if (mp[i][j] ==  X ) {           x2 = i;           y2 = j;           bb = true;           break;         }       }       if (bb) break;     }     if (x1 > x2 || y1 > y2) {       puts( NO );       return 0;     }     for (int i = x1; i <= x2; i++)       for (int j = y1; j <= y2; j++) {         if (mp[i][j] ==  . ) {           puts( NO );           return 0;         }         mp[i][j] =  . ;       }     for (int i = 0; i < n; i++)       for (int j = 0; j < m; j++)         if (mp[i][j] ==  X ) {           puts( NO );           return 0;         }     puts( YES );     return 0;   }   