#include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <string>
#include <tuple>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <random>
//#include "toollib.h"
#define INT_MAX 2147483647
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#pragma warning (disable:4018)

using namespace std;
typedef long long int lint;

//***** Main Program *****

int main() {
	int n;
	string S, T;
	cin >> n >> S >> T;
	int ret = 0;
	Loop(i, n) {
		if (S[i] != T[i]) ret++;
	}
	cout << ret << endl;
	return 0;
}