using System;

public class Program

{

    public static void Main()

    {

String BirthMonthAsString;

int BirthMonth;

String BirthDayAsString;

int BirthDay;

        Console.WriteLine("Please enter a birth month as a number");

        BirthMonthAsString = Console.ReadLine();

        Console.WriteLine("Please enter a Birth day");

        BirthDayAsString = Console.ReadLine();

        BirthMonth = Convert.ToInt32(BirthMonthAsString);

        BirthDay = Convert.ToInt32(BirthDayAsString);

        if(BirthMonth <1 || BirthMonth > 12) 

           Console.WriteLine("error, please run again and enter a valid month as a number.");

        else

        {

            //Check if month has 30 days

            if(BirthMonth == 4 || BirthMonth == 6 || BirthMonth == 9 || BirthMonth == 11)

                {if(BirthDay < 1 || BirthDay > 30)

                    Console.WriteLine("error, please run again and enter a valid day of the month.");

​

                else

                    Console.WriteLine(BirthMonth + "-" + BirthDay+" is a valid Birth date.");

​

​

                }

            else

                //Check if month has 29 days

            {if(BirthMonth == 2)

                if(BirthDay > 29 || BirthDay < 1)

                    Console.WriteLine("error, please run again and enter a valid day of the month.");

                else 

                    Console.WriteLine(BirthMonth + "-" + BirthDay+" is a valid Birth date.");

                //the month has 31 days

            else    

                if(BirthDay > 31 || BirthDay < 1)

                    Console.WriteLine("error, please run again and enter a valid day of the month.");

                else 

                    Console.WriteLine(BirthMonth + "-" + BirthDay+" is a valid Birth date.");

            }

        }

    }

}