using System;

public class Program

{

    public static void Main()

    {

        var date = Convert.ToDateTime("6/30/2020 11:59:00 PM");

        Console.WriteLine("date :"  + date);

        Console.WriteLine();

        Console.WriteLine();

        Console.WriteLine("date to timestamp");

        var UnixTimeStamp = date.Subtract(new DateTime(1970, 1, 1)).TotalSeconds;

        var timeStamp = Convert.ToInt64(UnixTimeStamp).ToString();

        Console.WriteLine("TimeStamp :"  + timeStamp);

        Console.WriteLine();

        Console.WriteLine();

        Console.WriteLine("Timestamp to date");

        var TimeStampToConvert = 1593561540;

        var timeStamptoDateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc).AddSeconds(TimeStampToConvert).ToUniversalTime();

        Console.WriteLine("TimeStampToDateTime :"  + timeStamptoDateTime);

    }

}