using System;

public class Program

{

    public static void Main()

    {

        int? filled = 5;

        int? empty = null;

        Console.WriteLine((10 - filled != null) ? (10 - filled).ToString() : "null");

        Console.WriteLine((10 - empty != null) ? (10 - empty).ToString() : "null");

        Console.WriteLine(10 > (10 - filled));

        Console.WriteLine(10 > (10 - empty));

​

        Console.WriteLine(10 < (10 - filled));

        Console.WriteLine(10 < (10 - empty));

    }

}