using System;

public class Program

{

    public static void Main()

    {

        int s1,  s11 ,s2, eded , max;

        eded = int.Parse(Console.ReadLine());

        s1 = eded/100;

        s2= eded/10%10;

        s11 = eded%10;

        max = s1 ;

        if(s11 > max) max = s11;

        if(s2 > max) max = s2;

        Console.WriteLine("Ən boyuk ədəd-" + max);

    }

}