#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 0x3f3f3f3f3f3f3f3f;
const int N = 2e3+11, P = 998244353;


void work(){
	int n; cin>>n;
	char s[N], t[N];
	cin>>s>>t;
	
	ll ans = 0;
	for(int i=0;i<n;i++) if(s[i] != t[i]) ans ++;
	cout<<ans<<endl;
}


int main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int t = 1;  //cin>>t; 
	while(t--) work(); 
	return 0;
}