#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETLINE( A ) string A; getline( cin , A ) 

int main()
{

  CIN( ll , n );
  CIN( string , S );
  CIN( string , T );
  ll answer = 0;

  for( ll i = 0 ; i < n ; i++ ){

    if( S[i] != T[i] ){

      answer++;

    }
    
  }

  cout << answer << endl;
  return 0;

}