using System;

public class Program

{

    public static void Main()

    {

                DateTime now = DateTime.UtcNow;

                DateTime soonestAlarm = now + TimeSpan.FromSeconds(61) - TimeSpan.FromSeconds(now.Second);

                DateTime oldAlarmTime = DateTime.UtcNow.AddMinutes(-5);

​

                if ((oldAlarmTime != null) && (oldAlarmTime <= soonestAlarm))

                {

                    soonestAlarm = oldAlarmTime + TimeSpan.FromSeconds(1);

                }

​

                TimeSpan timeToAlarm = soonestAlarm - now + TimeSpan.FromSeconds(1);

​

                Console.WriteLine(timeToAlarm.TotalMilliseconds);

    }

}