using System;

public class Program

{

    public static int Diff2(int num, int x)

    {

        if(num>=10)

        {

            num = num/10;

            Diff2(num, x);

        }

        else

            return Math.Abs(x-num);

    }

    public static int Diff(int num)

    {

        int x = num%10;

        if(num<10)

            return num;

        return Diff2(num, x);

    }

    public static void Main()

    {

        Console.WriteLine(Diff(123123));

    }

}