func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     string s, t, p =   ;     cin >> s >> t;     int n = s.size();     int c = 0;     for (int i = 0; i < n; i++)       if (s[i] != t[i]) c++;     if (c % 2) {       cout <<  impossible ;       return 0;     }     for (int i = 0; i < n; i++) {       if (s[i] == t[i]) {         p += s[i];         continue;       }       if (c)         p += s[i], c -= 2;       else         p += t[i];     }     cout << p << endl;     return 0;   }   