Require Import ZArith Lia. Local Open Scope Z_scope. Unset Lia Cache. Goal forall a q q0 q1 r r0 r1: Z, 0 <= a < 2 ^ 64 -> r1 = 4 * q + r -> 0 <= r < 4 -> a = 4 * q0 + r0 -> 0 <= r0 < 4 -> a + 4 = 2 ^ 64 * q1 + r1 -> 0 <= r1 < 2 ^ 64 -> r = r0. Proof. intros. (* subst. *) Time lia. Qed.