func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int x = 0;     char ch = getchar();     while (!isdigit(ch)) ch = getchar();     while (isdigit(ch)) x = x * 10 + ch -  0 , ch = getchar();     return x;   }   const int maxn = 100005;   int n;   long long zero = 0, one = 0, z1 = 0, o1 = 0;   char s[maxn], t[maxn];   int main() {     n = read();     scanf( %s%s , s, t);     for (int i = 0; i < n; ++i) {       if (s[i] ==  0 ) {         zero++;         if (t[i] ==  0 ) z1++;       } else {         one++;         if (t[i] ==  0 ) o1++;       }     }     printf( %lld n , z1 * one + o1 * zero - z1 * o1);     return 0;   }   