fact: Fixpoint foot_split {A} (L : list A) : (list A) * (option A) := match L with | nil => (nil, None) | h :: nil => (nil, Some h) | h :: L' => match foot_split L' with (L'', o) => (h :: L'', o) end end.
imports: Psatz List Arith.Div2 Even Relations RelationClasses PeanoNat Peano_dec Recdef Sorting Permutation Multiset