using System;

public class Program

{

    private static long _slidingExpiration = 900;

    public static void Main()

    {

        var timeStampVerified = ValidateTimeStamp(12345678, 12345679);

        System.Console.WriteLine(timeStampVerified);

        timeStampVerified = ValidateTimeStamp(12345679, 12345678);

        System.Console.WriteLine(timeStampVerified);

    }

    private static bool ValidateTimeStamp(long timeStamp, long newTimeStamp)

    {

        var timeDifference = Math.Abs(newTimeStamp - timeStamp);

        System.Console.WriteLine(timeDifference);

        return timeDifference <= Math.Abs(_slidingExpiration);

    }

}