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

#define int long long
#define forn(i, a, b) for (int i = a; i < b; i++)
#define print(a) cout << a << "\n"
#define printarr(a) for (int i = 0; i < (int)a.size(); i++) cout << a[i] << " "; cout << "\n"

typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;

#define srt(a) sort(a.begin(), a.end())
#define all(a) a.begin(), a.end()
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define popcount __builtin_popcountll

const int MOD = 1e9 + 7;

bool comp(pi a, pi b) {
     return (a.f == b.f) ? (a.s > b.s) : (a.f < b.f);
}

void solve(){
    int n; 
    cin >> n ; 
    string s1,s2;
    cin >> s1>>s2;
    int cnt = 0 ; 
    forn(i,0,n){
        if(s1[i]!=s2[i])cnt++;
    }

    cout<<cnt<<"\n";

}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    int t = 1;
    //cin >> t;
    while (t--)
        solve();

    return 0;
}