using System;

namespace ConsoleApplication16
{
    class Program
    {

        static string EGN;

        static bool IsLengthValid(string EGN)
        {
            if (EGN.Length != 10)
            {
                return false;
            }
            foreach (char c in EGN)
            {
                if (Char.IsLetter(c))
                {
                    return false;
                }
            }
            return true;
        }

        public static bool isMonthValid(month1, month2)
        {
            Console.WriteLine("EGN[2]=" + EGN[3]);
            string month = ((EGN.Substring(2, 1)));
            month1 = int.Parse(Console.ReadLine());
            if (month1!=0 && month1!=1)
            {
                return false;
            }
            return true;
        }


        static void Main(string[] args)
        {
            do
            {
                Console.WriteLine("Enter your EGN: ");
                string EGN = Console.ReadLine();
                Console.WriteLine("And it returns:" + isMonthValid(EGN));
                if (isMonthValid(EGN))
                {
                    Console.WriteLine("EGN is valid!");
                }
                else
                {
                    Console.WriteLine("This is not a valid EGN.");
                }
            }
            while (true);
        }
    }
}


/*public static bool (month1, month2)
if(month1!=0 && month1!=1)
{
return false
}
if (month2<0 || month2>9)
{
return false;
}


//(4,2)
//Vzimame 4etvyurtiq simvol if ot nego broim 2 simvola
*/