using System;

public class Program

{

    public static void Main()

    {

        DateTime dt = DateTime.Now;     

        DateTime dtUltimoDiaMesActual;

        dtUltimoDiaMesActual = new DateTime(dt.Year,dt.Month,1,dt.Hour,dt.Minute,0);        

        dtUltimoDiaMesActual=dtUltimoDiaMesActual.AddMonths(1).AddDays(-1);     

        Console.WriteLine(dtUltimoDiaMesActual.ToString("yyyyMMddhhMM"));

        Console.WriteLine(dtUltimoDiaMesActual.ToFileTimeUtc());

    }

}