using System;

​

public class Program

{

    public readonly static DateTime EPOCH_UNIX = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    private readonly static long MaxUnixSeconds = (long)(DateTime.MaxValue.ToUniversalTime() - EPOCH_UNIX).TotalSeconds;

    public static void Main()

    {

        // date with DST (Daylight savings time), e.g. 08/09/2092 (DD/MM/yyyy), 

        // is stored as, e.g. 3869074800 seconds, from EPOCH_UNIX, 

        // instead of 3869078400 (UTC, without offsets)

        DateTime dt = FromUnixTimeStamp(3869074800);

        Console.WriteLine("Date: {0:dd MMM yyyy HH:mm}", dt);

        // fix DST offset

        if (dt.Hour != 0)

        {

            int offset = 24 - dt.Hour;

            dt = dt.AddHours(offset);

            Console.WriteLine("Offset from 00h00m: {0}", offset);

        }

        // fix century (if date of birth)

        if (dt.Year > DateTime.UtcNow.Year)

            dt = dt.AddYears(-100);

        Console.WriteLine("Fixed Date: {0:dd MMM yyyy HH:mm}", dt);

    }

​

    public static DateTime FromUnixTimeStamp(long value)

    {

        return value > MaxUnixSeconds ? EPOCH_UNIX.AddMilliseconds(value) : EPOCH_UNIX.AddSeconds(value);

    }

}