using System;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        Regex r = new Regex(@"^[A-Z0-9]*$");

        string[] ss = new string[] {"Hello", "HELLO", "Hello 123", "HELLO 123", "HELLO123", ""};

        foreach(var s in ss) {

            Console.WriteLine("{0}\t{1}", s, s.All(c => (Char.IsLetter(c) && Char.IsUpper(c)) || Char.IsDigit(c)));

        }

    }

}