func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string s1, s2, t =   ;     cin >> s1 >> s2;     int n = s1.size(), c = 0, c1 = 0, c2 = 0;     for (int i = 0; i < n; i++) {       if (s1[i] != s2[i]) c++;     }     if (c % 2 != 0)       cout <<  impossible  << endl;     else {       c1 = c2 = c / 2;       for (int i = 0; i < n; i++) {         if (s1[i] == s2[i])           t += s1[i];         else if (s1[i] != s2[i]) {           if (c1 > 0) {             c1--;             t += s1[i];           } else if (c2 > 0) {             c2--;             t += s2[i];           }         }       }       cout << t << endl;     }   }   