Ltac Cong := auto 4 with cong.Ltac eCong := eauto with cong.

Lemma Cong_cases : forall A B C D, Cong A B C D \/ Cong A B D C \/ Cong B A C D \/ Cong B A D C \/ Cong C D A B \/ Cong C D B A \/ Cong D C A B \/ Cong D C B A -> Cong A B C D.