proposition: Lemma lpeg_nil_inv n c p : lpeg p c = [::] -> c = `c[p] :> configuration _ n.
proof: Proof. have := @rpeg_nil_inv _ c p. rewrite /lpeg; case: rpeg => //= a l. by rewrite rev_cons; case: rev. Qed.
imports: mathcomp(all_ssreflect) hanoi(extra gdist ghanoi ghanoi3)