using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;

public class Program
{

    public void Proc()
    {
        int len = int.Parse(Reader.ReadLine());
        string str1 = Reader.ReadLine();
        string str2 = Reader.ReadLine();
        int diff = 0;
        for (int i = 0; i < len; i++) {
            if(str1[i]!=str2[i]) {
                diff++;
            }
        }
        Console.WriteLine(diff);
    }


    public class Reader
    {
        private static StringReader sr;
        public static bool IsDebug = false;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (sr == null)
                {
                    sr = new StringReader(InputText.Trim());
                }
                return sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        private static string InputText = @"



8
hidamari
yunocchi


";
    }

    public static void Main(string[] args)
    {
#if DEBUG
        Reader.IsDebug = true;
#endif
        Program prg = new Program();
        prg.Proc();
    }
}