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

void solve() {
    int n;cin>>n;
    string s,s1;cin>>s>>s1;
    int cnt=0;
    for(int i=0;i<n;i++)
    {
        if(s[i]!=s1[i])
            cnt++;
    }
    cout<<cnt;

    

}

signed main() {
    int tt=1;
    //cin>>tt;
    while(tt--)
    {
        solve();
        cout<<'\n';
    }
}