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  1. countdown(0) :- !.
  2. countdown(X) :-
  3. 	number(X),
  4. 	X < 0.
  5. countdown(X) :-
  6. 	number(X),
  7. 	X>=0,
  8. 	write(X), nl,
  9. 	NX is X-1,
  10. 	countdown(NX).
Success #stdin #stdout 0.02s 68352KB
comments (?)
stdin 
countdown(4).
stdout 
GNU Prolog 1.3.1
By Daniel Diaz
Copyright (C) 1999-2009 Daniel Diaz
4
3
2
1

yes
https://ideone.com/rP5Ha
language:
Prolog (gprolog 1.4.5)
created:
14 years ago
visibility:
public

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