#include<iostream>
#include<string>
using namespace std;

int main()
{
	int n,sum=0;
	char S[1000], T[1000];
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> S[i];
	}
	for (int i = 0; i < n; i++)
	{
		cin >> T[i];
	}
	for (int i = 0; i < n; i++)
	{
		if (S[i] == T[i])
		{
			continue;
		}
		else if (S[i != T[i]])
		{
			sum++;
		}
	}
	cout << sum << endl;
	return 0;
}