fact: Definition ltb (x y : t) : bool := (fst x <? fst y) || ((fst x =? fst y) && (snd x <? snd y)).
imports: Coq.QArith.QArith Coq.Structures.Orders Coq.micromega.Lia Coq.Bool.Bool Coq.Sorting.Mergesort Coq.Lists.List Coq.ZArith.ZArith PerformanceExperiments.Sandbox