using System;

public class Program

{

    public static void Main()

    {

        long unixTimestamp = ToUnixTimestamp(PegaHoraBrasilia().AddMinutes(2));

        Console.WriteLine("Unix: {0}",unixTimestamp);

        DateTime dt = ToDateTime(unixTimestamp);

        Console.WriteLine("Datetime: {0}",dt);

    }

     public static long ToUnixTimestamp( DateTime target)

        {

            var date = new DateTime(1970, 1, 1, 0, 0, 0, target.Kind);

            var unixTimestamp = System.Convert.ToInt64((target - date).TotalSeconds);

​

            return unixTimestamp;

        }

​

        public static DateTime ToDateTime(long timestamp)

        {

            var dateTime = new DateTime(1970, 1, 1, 0, 0, 0);

​

            return dateTime.AddSeconds(timestamp);

        }

    public static DateTime PegaHoraBrasilia() {

        return TimeZoneInfo.ConvertTime(DateTime.Now, TimeZoneInfo.FindSystemTimeZoneById("E. South America Standard Time"));

}

}