intros n m p H H1;
apply Z.lt_gt; apply Zmult_lt_compat_l_rev with p; auto with zarith.
Qed.

(* Specifications: *)
Theorem Zmult_gt_neg_compat_l_rev:
forall n m p : Z, (0 > p)%Z -> (p * n > p * m)%Z -> (m > n)%Z.