using System;

public class Program

{

    public static void Main()

    {

        string measure_time="2018-11-19T01:55:28.173Z";

        string created_at="2017-05-06T06:34:09Z";

        DateTime time= string.IsNullOrWhiteSpace(measure_time) ? Convert.ToDateTime(Convert.ToDateTime(created_at).ToString("yyyy-MM-dd HH:mm")):Convert.ToDateTime(Convert.ToDateTime(created_at).ToString("yyyy-MM-dd HH:mm"));

        Console.WriteLine(time.ToString("yyyy-MM-dd HH:mm:ss.fff"));

    }

}