#include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     string s, t;     cin >> s >> t;     int cost = 0;     for (int i = 0; i < n;) {       if (s[i] != t[i]) {         if (i + 1 < n && s[i] != s[i + 1] && s[i + 1] != t[i + 1]) {           i += 2;         } else {           i++;         }         cost++;       } else {         i++;       }     }     cout << cost << endl;     return 0;   }   