proposition: Fact ordS_subproof n (i : 'I_n) : i.+1 %% n < n.
proof: Proof. by case: n i => [|n] [m m_lt]//=; rewrite ltn_pmod. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path div)