using System;
public class Program
{
public static void Main()
Console.WriteLine("Hello World");
bool? t = true;
bool? f = false;
bool? n = null;
if(t == true)
Console.WriteLine("t is true");
}
if(f == false)
Console.WriteLine("f is false");
if(n != false)
Console.WriteLine("n is not false");
if(n != true)
Console.WriteLine("n is not true");