// BISMILLAH
// created by kamran
// Date: 2026-01-03 13:02

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

#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define  int long long
#define nl endl
signed main() {
    fast;
int n;
cin>>n;
    string x;
    string y;
    cin>>x>>y;
    int cnt=0;
    for(int i=0;i<n;i++){
if(x[i] != y[i])cnt++;
    }

cout<<cnt<<nl;
    return 0;
}