func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string a, b;     cin >> a >> b;     int n = a.size();     int f = 0, s = 0;     for (int i = 0; i < n; ++i)       if (a[i] != b[i]) {         if (a[i] ==  4 )           f++;         else           s++;       }     int ans = min(f, s);     ans += (f - ans) + (s - ans);     cout << ans;     return 0;   }   