using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string dateRange = "Mon Oct 07 2019 00:00:00 GMT-0400 (Eastern Daylight Time)Sat Nov 23 2019 00:00:00 GMT-0500 (Eastern Standard Time)";

        string[] parts = dateRange.Split('(',')');

        string format = "ddd MMM dd yyyy HH:mm:ss 'GMT'zzz";

        DateTimeOffset start = DateTimeOffset.ParseExact(parts[0].Trim(), format, CultureInfo.InvariantCulture);

        DateTimeOffset end = DateTimeOffset.ParseExact(parts[2].Trim(), format, CultureInfo.InvariantCulture);

        Console.WriteLine(start.ToString("o"));

        Console.WriteLine(end.ToString("o"));

    }

}