func_code_string: #include <bits/stdc++.h>   using namespace std;   string itosm(long long x) {     if (x == 0) return  0 ;     string ans =   ;     while (x > 0) {       ans += ((x % 10) +  0 );       x /= 10;     }     reverse(ans.begin(), ans.end());     return ans;   }   long long stoim(string str) {     long long ans = 0;     long long k = 1;     for (int i = str.length() - 1; i >= 0; i--) {       ans += (str[i] -  0 ) * k;       k *= 10;     }     return ans;   }   const long long infll = 1e18 + 3;   const int inf = 1009000999;   const double eps = 1e-6;   const int maxn = 1e6 + 77;   const int baseint = 1000200013;   const long long basell = 1e18 + 3;   const long double PI = acos(-1.0);   int main() {     srand(228228);     ios_base::sync_with_stdio(0);     ;     string t, s, p =   ;     cin >> t >> s;     int n = s.length();     while (p.length() != n) p +=  0 ;     int cnt = 0;     for (int i = (0); i < (n); i++) {       if (s[i] == t[i])         p[i] = s[i];       else         cnt++;     }     if (cnt % 2) {       cout <<  impossible ;       return 0;     }     cnt = 0;     for (int i = (0); i < (n); i++) {       if (s[i] != t[i]) {         if (cnt <= 0) {           p[i] = s[i];           cnt++;         } else {           p[i] = t[i];           cnt--;         }       }     }     cout << p;     return 0;   }   