/*-----------------------------------------------------------------------------
  Fibonacci numbers
-----------------------------------------------------------------------------*/

ffib(0,0).
ffib(1,1).
ffib(M,N) :-
	M > 1, 
	M1 is M-1, 
	M2 is M-2,
	ffib(M1,N1), 
	ffib(M2,N2),
	N is N1+N2.
