A tricky one !!

Recently i came to know about a C program without 'main'
itz so tricky and very interesting....

#include "stdio.h"
#define decode(n,s,u,t) n##t##u##s
#define begin decode(m,n,i,a)

int begin()
{
printf(" \nhello ");
getch();
}


where ' ## ' --> token pasting operator for concatinating words...
see a tricky one rite..