d(1234567).
b([-D, -D + 1, -2, -1, 0, 1, 2, D - 2, D - 1]) :-
d(D).
print_array([]).
print_array([H|T]) :-
NegH is -H,
format('~d -> ~d~n', [H, NegH]),
print_array(T).
main :-
b(B),
print_array(B).