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

#define nl cout<<endl;
#define YN(condition) cout<<(condition?"YES":"NO")
#define yn(condition) cout<<(condition?"Yes":"No")

#define int long long
#define lint __int128
#define ll long long
#define ld long double
#define pii pair<int,int>
#define inf 1e17
#define MOD 1000000007

#define ai(n) array<int,n>
#define ac(n) array<char,n>
#define vi vector<int>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define vpi vector<pair<int,int>>
#define vvi vector<vector<int>>
#define mp map<int,int>
#define pq priority_queue<int>
#define pqmin priority_queue<int, vector<int>, greater<int>>
#define pqminpair priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>>

#define f(i,s,e) for(int i=s;i<e;i++)
#define fn(i,s,e) for(int i=s;i>=e;i--)
#define printv(vec) for(auto &value: vec) cout<<value<<" ";
#define inputv(vec) for(auto &value: vec) cin>>value;

#define pb push_back
#define pp pop_back
#define all(s) s.begin(), s.end()
#define sa(vec) sort(vec.begin(), vec.end())
#define sd(vec) sort(vec.begin(), vec.end(), [](int a, int b){return a>b;})

#define fastnuces ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);int t = 1;
int test=0;
void solve(){
    int n;
    cin>>n;
    string a, b;
    cin>>a>>b;
    int  ans=0;
    f(i, 0, n){
        ans+=(a[i]!=b[i]);
    }
    cout<<ans;
}
signed main() {
    fastnuces;
    // cin >> t;
    while (t--) {
        test++;
        solve();
        nl
    }
    return 0;
}