proposition: Lemma half_le2 m: (m.+1)./2 <= m.
proof: Proof. by case: m => // m /=; rewrite ltnS half_le1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)