#define A

#define B

​

using System;

​

public class Program

{

    public static void Main()

    {

#if A

#if B

        Console.WriteLine("A and B");

#else

        Console.WriteLine("A and not B");

#endif

#else

#if B

        Console.WriteLine("B and not A");

#else

        Console.WriteLine("neither A nor B");

#endif

#endif

​

    }

}