func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   char mp[510][510];   int minln, maxln, minrw, maxrw, cnt;   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= n; i++) scanf( %s , mp[i] + 1);     minln = n + 1;     maxln = 0;     minrw = m + 1;     maxrw = 0;     for (int i = 1; i <= n; i++)       for (int j = 1; j <= m; j++)         if (mp[i][j] ==  X ) {           minln = min(i, minln);           minrw = min(j, minrw);           maxln = max(i, maxln);           maxrw = max(j, maxrw);           cnt++;         }     if (minln > maxln || minrw > maxrw ||         (maxln - minln + 1) * (maxrw - minrw + 1) != cnt)       printf( NO n );     else       printf( YES n );     return 0;   }   