using System;

public class Program

{

    public static void Main()

    {

        bool? result = null;

        if (result == false)

        {

            Console.WriteLine("YES");

        }else{

            Console.WriteLine("NO");

        }

        if (result != true)

        {

            Console.WriteLine("YES");

        }else{

            Console.WriteLine("NO");

        }

    }

​

}