func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string a, b;     cin >> a >> b;     int x = 0, y = 0, z = 0;     for (int i = 0; i < a.length(); i++) {       if (a[i] != b[i]) {         if (a[i] ==  4 )           x++;         else           y++;       }     }     cout << min(x, y) + abs(x - y);   }   