(n : Int) : Int := match n with | posS n => posS (S n) | 0 => 1 | -1 => 0 | negS (S n) => negS n end.
Require Import Basics.Overture Basics.Nat Basics.Tactics Basics.Decidable Basics.Equivalences Basics.PathGroupoids Types.Paths Types.Universe. Require Import Spaces.Nat.Core.