/*事実と規則*/
choice([ ],[ ]).
choice([H|T],[0|Y]):-choice(T,Y).
choice([H|T],[H|Y]):-choice(T,Y).
sum([ ],0).
sum([H|T],SUM):-sum(T,S), SUM is H+S.
solve(ANS,SUM):-choice([3,14,6,9],ANS),sum(ANS,SUM).
?- solve(ANS,12).