#include <stdio.h>
#include <malloc.h>

char str[60000];
int str_len = 0;

/// <summary>
/// 入力された数字を返す
/// </summary>
/// <returns></returns>
int ReadNum() {
	int negate = 0;
	char c = getchar();
	int num = 0;
	int numCnt = 0;
	while (c != '\n') {
		if (c == '-') {
			negate = 1;
		}
		else {
			num = num * 10 + c - '0';
		}

		c = getchar();
	}
	if (negate == 1) {
		num *= -1;
	}
	return num;
}

/// <summary>
/// グローバル変数strの中身を入力された文字列で上書きする
/// </summary>
void ReadString() {
	char c = getchar();
	str_len = 0;

	while (c != '\n') {
		str[str_len] = c;
		c = getchar();
		str_len++;
	}
}

int main()
{
	int cnt = 0;
	int n = ReadNum();
	char* str1;
	char* str2;
	str1 = (char*)malloc(sizeof(char) * n);
	str2 = (char*)malloc(sizeof(char) * n);
	ReadString();
	for (int i = 0;i < n;i++) str1[i] = str[i];
	ReadString();
	for (int i = 0;i < n;i++) str2[i] = str[i];
	for (int i = 0;i < n;i++) {
		if (str1[i] != str2[i]) cnt++;
	}
	printf("%d\n",cnt);
}