:-style_check(-singleton).
:-dynamic(cones/1).

% ice-cream cones.
scoop(vanilla). scoop(strawberry). scoop(chocolate).

cone(A,B,C):-scoop(A), scoop(B), scoop(C).

cones(0).

count:-retract(cones(X)), Y is X+1, assert(cones(Y)).

go:-cone(X,Y,Z), count,fail; cones(Number), write(number_cones(Number)).