q2 (crypt (X, Y)):- q1 (X), q1 (Y).
q2 (crypt (X, Y)):- q2 (X), q1 (Y).
q1 (plus (X, Y)):- q1 (X), q1 (Y).
q2 (plus (X, Y)):- q1 (X), q2 (Y).
q2 (plus (X, Y)):- q2 (X), q1 (Y).
q1 (plus (X, Y)):- q2 (X), q2 (Y).