func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     int n, m;     cin >> n >> m;     char grid[n][m];     int x1 = 1e9, y1 = 1e9, x2 = 0, y2 = 0;     for (int i = 0; i < n; i++)       for (int j = 0; j < m; j++) {         cin >> grid[i][j];         if (grid[i][j] ==  X )           x1 = min(x1, i), y1 = min(y1, j), x2 = max(x2, i), y2 = max(y2, j);       }     bool ok = true;     for (int i = x1; i <= x2; i++)       for (int j = y1; j <= y2; j++)         if (grid[i][j] !=  X ) ok = false;     if (ok)       cout <<  YES  << endl;     else       cout <<  NO  << endl;     return 0;   }   