#include<bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define rep(i,n) for(int i = 0; i < (n); ++i)

int main(){
  int N; cin >> N;
  string S, T; cin >> S >> T;
  reverse(all(S));

  int ans = 0;
  rep(i, N) if(S[i]!=T[i]) ans++;
  cout << ans << endl;
}