using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        IEnumerable<Custom> test = new List<Custom> {new Custom { time = new DateTime(2021, 6,6)} ,new Custom { time = new DateTime(2019, 6,6)}, new Custom { time = new DateTime(2020, 6,6)}};

        test = test.OrderByDescending(t => t.time);

        foreach(var i in test) {

            Console.WriteLine(i.time);

        }

        Console.WriteLine("Hello World");

    }

    class Custom {

        public DateTime time {get;set;}

    }

}