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

namespace EgnValidating
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please enter EGN !");
            CheckEGN();
        }
        static void CheckEGN()
        {
            string EGN = Console.ReadLine();
            if (EGN.Any(Char.IsSymbol) || EGN.Length != 10 || EGN.Any(Char.IsLetter))
            {
                Console.WriteLine("Invalid format.EGN must contain only digits ! ");
            }
            else
            {
                string yy = EGN.Substring(0, 2);
                string mm = EGN.Substring(2, 2);
                string dd = EGN.Substring(4, 2);
                if (int.Parse(mm) > 31)
                {
                    yy = "20" + yy;
                    mm = (int.Parse(mm) - 40).ToString();
                }
                else if (int.Parse(mm) > 20 && int.Parse(mm) < 31)
                {
                    yy = "18" + yy;
                    mm = (int.Parse(mm) - 20).ToString();
                }
                else
                {
                    yy = "19" + yy;
                }
                Console.WriteLine("Valid EGN format");

            }
        }
    }
}