using System;

using System.Globalization;

​

public class Program

{

    public static void Main()

    {

        var pero= "36903";

        var a="12.1.2001 0:00:00";

                var b = Convert.ToDateTime(

                    a,

                    CultureInfo.CreateSpecificCulture("hr-HR")

                );

        //Console.WriteLine(b.Ticks);

        try{

        var c = Convert.ToDouble(a);

            Console.WriteLine(Convert.ToDouble(a));

        }

        catch (Exception ex){

            Console.WriteLine(ex.Message);

        }

        Console.WriteLine(DateTime.FromOADate(Convert.ToDouble(pero)));

        //Console.WriteLine(DateTime.FromOADate(a.Ticks));

    }

}