snowflake(1, [60,-60,180]).
snowflake(N, Ls) :-
	N > 1,
	N1 is N - 1,
	snowflake(N1, Ls0),
	sf(Ls0, Ls).

sf([],[]).
sf([X|Xs], [X,A,B,C|Ys]) :-
	( X =< 120
	-> A is X + 60
	; A is X - 300
	),
	( X > -120
	-> B is X - 60
	; B is X + 300
	),
	C is X,
	sf(Xs, Ys).