BeerTime2.cs

using System;

class Program
{
    private static void Main()
    {
        string input = Console.ReadLine();

        DateTime date;
        if (DateTime.TryParse(input, out date))
        {
            if (date.Hour >= 13 || date.Hour < 3)
            {
                Console.WriteLine("beer time");
            }
            else
            {
                Console.WriteLine("non-beer time");
            }
        }
        else
        {
            Console.WriteLine("invalid time");
        }
    }
}