#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here
    int n; cin >> n; 
    string a,b; cin >> a >> b;
    int result=0;
    for(int i=0;i<n;++i) {
        if(a[i]==b[i]) continue;
        int j=i;
        for(;j<n;++j) {
            if(a[j]!=b[j]) continue;
            else break;
        }
        i=j;
        ++result;
    }
    cout << result << "\n";
	return 0;
}