/*
 * C# Program to Demonstrate the Working #define Preprocessor
 */
#define B
#define A
#undef A
using System;
class Program
{
    static void Main()
    {
#if A
        Console.WriteLine("'A' is Displayed Based on the undef Directive ");
#elif B
        Console.WriteLine("'B' is Displayed Based on the undef Directive");
#endif
        Console.ReadLine();
    }
}

/*
'B' is Displayed Based on the undef Directive