case (ZquotientProp m 1); auto.
red in |- *; intros; discriminate.
intros z (H1, (H2, H3)).
pattern m at 2 in |- *; rewrite H1; replace z with 0%Z; try ring.
generalize H3; case z; simpl in |- *; auto; intros p; case p;
unfold Zlt in |- *; simpl in |- *; intros; discriminate.
Qed.

Theorem Zdivides1 : forall m : Z, Zdivides m 1.
intros m; exists m; auto with zarith.