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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int nn = int.Parse(Console.ReadLine());
            var va = Console.ReadLine();
            var vb = Console.ReadLine();
            var vc = vb.Select((n, i) => n == va[i] ? 0 : 1);
            Console.WriteLine(vc.Sum());
            Console.ReadLine();
        }
    }
}