func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     long long n;     cin >> n;     vector<string> a(n);     for (long long i = 0; i < n; ++i) {       cin >> a[i];     }     unordered_set<char> diagonal, non_diagonal;     for (long long i = 0; i < n; ++i) {       for (long long j = 0; j < n; ++j) {         if (i == j) {           diagonal.insert(a[i][j]);         } else if (j == n - i - 1) {           diagonal.insert(a[i][j]);         } else {           non_diagonal.insert(a[i][j]);         }       }     }     if (diagonal.size() == 1 && non_diagonal.size() == 1) {       for (char a : diagonal) {         for (char b : non_diagonal) {           if (a != b) {             cout <<  YES ;           } else {             cout <<  NO ;           }         }       }     } else {       cout <<  NO ;     }   }   int32_t main() {     ios::sync_with_stdio(false);     cin.tie(0);     solve();   }   