func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long N = 2e5 + 5;   const long long NN = 1e9 + 5;   char a[150][150];   map<char, bool> mp, mp1;   bool used[150][150];   long long n, m;   vector<char> v;   int main() {     cin >> n >> m;     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         cin >> a[i][j];       }     }     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         for (int l = 1; l <= m; l++) {           if (l != j && a[i][j] == a[i][l]) {             used[i][l] = true;           }         }         for (int l = 1; l <= n; l++) {           if (l != i && a[l][j] == a[i][j]) {             used[i][j] = true;           }         }       }     }     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         if (!used[i][j]) {           v.push_back(a[i][j]);         }       }     }     for (int i = 0; i < (int)v.size(); i++) {       cout << v[i];     }   }   