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

const int N = 100005;


vector<int> graph[N];


vector<int> sieve(int n) {
    vector<bool> isPrime(n + 1, true);
    isPrime[0] = isPrime[1] = false;

    for (int i = 2; i * i <= n; i++) {
        if (isPrime[i]) {
            for (int j = i * i; j <= n; j += i) {
                isPrime[j] = false;
            }
        }
    }

    vector<int> primes;
    for (int i = 2; i <= n; i++) {
        if (isPrime[i]) primes.push_back(i);
    }

    return primes;
}



void solve(){

int n;
cin>>n;
string s,t;
cin>>s>>t;


// cout<<s<<t;

int cnt =0;
for(int i=0; i <n;i ++){
    if(s[i] != t[i]) cnt++;

}

cout<<cnt;

}

signed main() {
    int t =1; 

    // cin >>t;

    while(t--){
        solve();
        cout<<endl;
    }

}