using System;

public class Program

{

    public static void Main()

    {

        var yourDate = new DateTime(2023, 09, 14, 0, 0, 0);

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

        Console.WriteLine( (yourDate-unixTime).TotalMilliseconds );

    }

}