func_code_string: #include <bits/stdc++.h>   using namespace std;   long long a[503400], b[477574], c[534567], d, e, i, j, r, m, y, k, l, n, s, z,       x, t, tt;   string p[3456], q, qq;   map<long long, long long> zz;   int main() {     cin >> n >> m;     for (i = 1; i <= n; i++) cin >> p[i];     cin >> x;     q = p[x];     a[x] = 1;     t = q.size();     for (i = 1; i < m; i++) {       cin >> y;       a[y] = 1;       if (p[y].size() != t) {         cout <<  No ;         return 0;       }       for (j = 0; j < t; j++) {         if (q[j] ==  ? ) continue;         if (p[y][j] != q[j]) q[j] =  ? ;       }     }     for (i = 1; i <= n; i++) {       if (a[i] == 1) continue;       if (p[i].size() != t) continue;       x = 0;       for (j = 0; j < t; j++) {         if (q[j] ==  ? ) continue;         if (q[j] != p[i][j]) x = 1;       }       if (x == 0) {         cout <<  No ;         return 0;       }     }     cout <<  Yes  << endl << q;   }   