using System;

public class Program

{

    public static void Main()

    {

Console.Write("Input a string: ");

        string str = Console.ReadLine();

         if (str.Length < 4) 

           Console.WriteLine(str.ToUpper());

         else

           Console.WriteLine(str.Substring(0, 4).ToLower() + str.Substring(4, str.Length -4));  }

}