func_code_string: #include <bits/stdc++.h>   using namespace std;   int main(int argc, char **argv) {     ios_base::sync_with_stdio(false);     cin.tie(0);     int m, n;     cin >> n >> m;     vector<string> s(n);     vector<pair<int, int>> t(n, {-1, -1});     for (int i = 0; i < n; i++) cin >> s[i];     bool ok = true;     for (int i = 0; i < n; i++) {       int k = 0;       for (int j = 0; j < m; j++) {         if (s[i][j] ==  X ) {           if (!j || s[i][j - 1] ==  . ) k++;           if (t[i].first < 0) t[i].first = j;           t[i].second = j;         }       }       if (k > 1) ok = false;     }     int k = 0;     pair<int, int> u({-1, -1});     for (int i = 0; i < n; i++) {       if (t[i].first < 0) continue;       if (!i || t[i - 1].first < 0) k++;       if (u.first < 0) u = t[i];       if (u != t[i]) ok = false;     }     if (k > 1) ok = false;     cout << (ok ?  YES  :  NO ) << endl;     return 0;   }   