using System;

public class Program

{

    public static void Main()

    {

        Test(null);

        Test(false);

        Test(true);

    }

    public static void Test( bool? t ) {

        try {

            Console.WriteLine( t.ToString() + " : " + ( t == true ? "true" : "not true" ) );

        } catch (Exception e) {

            Console.WriteLine(e.Message);

        }

    }

}