using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello! A leap year is something that occurs every four years, in which an extra day, Feburary 29th, is added.");

        Console.WriteLine("This happens in order to synchronize the calendars created by humans, with the Earth's orbit around the sun, which takes 365.25 days.");

        Console.WriteLine("The problem is that during common years, the extra .25 days which are needed for Earth to complete a full orbit, are not added.");

        Console.WriteLine("So because of this, the human calendar is faster than the solar year, which would end up creating a drift, ");

        Console.WriteLine("in wich the calendar year would be off by about one day after four years.");

        Console.WriteLine(" ");

        Start:

            Console.WriteLine("Enter a year to find out if it is a leap year, or a common year.");

        string input = Console.ReadLine();

        uint year;

        Console.Clear();

        if (uint.TryParse(input, out year))

        {

            if (year < 1582)

            {

                Console.WriteLine("Please enter a higher year. This is because in 1582, the current calendar, the Gregorian calendar, was first put into place.");

                goto Start;

            }

​

            if (year > 3000)

            {

                Console.WriteLine("Don't think so far into the future.");

                goto Start;

            }

​

            if (year >= 1582 && year <= 3000)

            {

                if (year % 4 != 0)

                    Console.WriteLine(year + " is a commmon year.");

                else if (year % 100 != 0)

                    Console.WriteLine(year + " is a leap year.");

                else if (year % 400 != 0)

                    Console.WriteLine(year + " is a common year.");

                else

                    Console.WriteLine(year + " is a leap year.");

                goto Start;

            }

        }

        else

        {

            Console.WriteLine("Please enter a positive integer.");

            goto Start;

        }

    }

}