proposition: Lemma predn_int (n : nat) : 0 < n -> n.-1%:Z = n - 1.
proof: Proof. by case: n=> // n _ /=; rewrite subn1. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)