#include <bits/stdc++.h>
#ifndef ONLINE_JUDGE
    #include <debug.hpp>
#else
    #define debug(...) 42
#endif
using namespace std;
#define int long long

void solve(){
    int n;
    string a,b;
    cin>>n>>a>>b;
    int ans =0;
    for(int i=0;i<n;++i){
        if(a[i]!=b[i])++ans;
    }
    cout<<ans<<endl;
}

int32_t main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int t = 1;
    // cin>>t;
    int x = 1;
    while(t--){
        debug(x);
        ++x;
        solve();
    } 
    return 0;
}