using System;

public class Program

{

    public static void Main()

    {

        int DAY = 86400;

        DateTime EpochTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

        DateTime utcNow = DateTime.UtcNow;

        int unixTime = (int)utcNow.Subtract(EpochTime).TotalSeconds;

        int secondsOffset = -DAY;

        int otherTime = unixTime + secondsOffset;

        DateTime otherDateTime = EpochTime.AddSeconds(otherTime);

        TimeSpan timeUntil = (otherTime - unixTime) > 0 ? TimeSpan.FromSeconds(otherTime - unixTime) : TimeSpan.FromSeconds(0);     

        //TimeSpan timeLeft = (unixTime - otherTime) > 0 ? TimeSpan.FromSeconds(unixTime - otherTime) : TimeSpan.FromSeconds(0);        

        TimeSpan timePast = (unixTime - otherTime) > 0 ? TimeSpan.FromSeconds(unixTime - otherTime) : TimeSpan.FromSeconds(0);

​

        Console.WriteLine(string.Format("Now: -- {0}", unixTime));      

        Console.WriteLine(string.Format("Other: -- {0} -- ", otherTime));   

        Console.WriteLine(string.Format("NowDT: -- {0} -- ", utcNow));      

        Console.WriteLine(string.Format("OtherDT: -- {0} -- ", otherDateTime));

        Console.WriteLine(string.Format("TimeUntil: -- {0} -- ", timeUntil));   

        //Console.WriteLine(string.Format("TimeLeft: -- {0} -- ", timeLeft));       

        Console.WriteLine(string.Format("TimePast: -- {0} -- ", timePast));

​

​

​

    }

}