package no224;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[] s = sc.next().toCharArray();
		char[] t = sc.next().toCharArray();
		int dist = 0;
		for(int i=0;i<n;i++) {
			if (s[i] != t[i]) {
				dist++;
			}
		}
		System.out.println(dist);
	}

}