#ifdef ONPC
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<pair<int,int>> vpi;
typedef pair<int,int> pi;
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define popcount __builtin_popcountll
#define forn(i,a,b) for (int i = a; i < b; i++)

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

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t=1;
    // cin >> t;
    forn(i,0,t){
        solve();
    }
    #ifdef ONPC
    cerr << endl
         << "finished in " << clock() * 1.0 / CLOCKS_PER_SEC << " sec" << endl;
    #endif
}