func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     char a[1000000], b[1000000];     int n;     cin >> n >> a;     int l = strlen(a);     for (int i = 1; i < n; i++) {       cin >> b;       for (int j = 0; j < l; j++) {         if (a[j] ==  ? )           a[j] = b[j];         else if (b[j] ==  ? )           continue;         else if (a[j] != b[j])           a[j] =  0 ;       }     }     for (int i = 0; i < l; i++) {       if (a[i] ==  0 )         a[i] =  ? ;       else if (a[i] ==  ? )         a[i] =  x ;     }     cout << a;     return 0;   }   