using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        DoDates(new DateTime(2020, 12, 1));

        // next leap year: Thursday, February 29 2024

        DoDates(new DateTime(2024, 12, 1));

        Console.WriteLine(DateTime.UtcNow);

    }

    private static void DoDates(DateTime endQuarterDate)

    {

        var lastDate = new DateTime(endQuarterDate.Year, endQuarterDate.Month, DateTime.DaysInMonth(endQuarterDate.Year, endQuarterDate.Month));

        var startDate = lastDate.AddYears(-1).AddDays(1);

        Console.WriteLine(startDate.ToShortDateString());

        Console.WriteLine(lastDate.ToShortDateString());

        Console.WriteLine("------------------------------------------------");

    }

}