proposition: Lemma unitFpE x : ((x%:R : 'F_p) \is a GRing.unit) = coprime p x.
proof: Proof. by rewrite pdiv_id // unitZpE // prime_gt1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool choice eqtype ssrnat seq div) mathcomp(fintype bigop finset prime fingroup) mathcomp(ssralg finalg countalg)