#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define io ios::sync_with_stdio(false); cin.tie(0);
#define int long long int
#define ld long double
#define vi vector<int>
#define pii pair<int, int>
#define pb push_back
#define F first
#define S second
#define MP make_pair
#define all(v) v.begin(), v.end()
#define forn(a, n) for(int i = a ; i < n ; i++)
#define yesno(b) cout << ((b)? "YES" : "NO")
#define nl cout << "\n"
#define print(v,a) for(auto _ : v) cout << _ << a;
#define MOD 998244353ll
#define MOD2 1000000007ll
#define FL(i, a, n) for(int i = a ; i < n ; i++)
#define FR(i, a, n) for(int i = a ; i >= n ; i--)
const int inf = 1e17 + 1;

void solve(){
    int n;
    string s, t;
    cin >> n >> s >> t;

    int ans = 0;
    forn(0, n) if(s[i] != t[i]) ans++;
    cout << ans;
}

signed main(){
    io;
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);

    int t = 1;
    // cin >> t;
    // auto st = chrono::high_resolution_clock::now();
    forn(1, t + 1){
        // cout << "Case #" << i << ": ";
        solve();
        nl;
    }

    return 0;
}