func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int m, nn, o, p;   int main() {     long long int n;     cin >> n;     string a, b;     cin >> a >> b;     for (int i = 0; i < n; i++)       if (a[i] ==  0 ) {         if (b[i] ==  0 )           m++;         else           nn++;       } else {         if (b[i] ==  0 )           o++;         else           p++;       }     cout << m * p + m * o + nn * o << endl;   }   