min 0 y 0 min s x 0 0 min s x s y min x y len nil 0 len cons x xs s len xs sum x 0 x sum x s y s sum x y le 0 x true le s x 0 false le s x s y le x y take 0 cons y ys y take s x cons y ys take x ys addList x y if le 0 min len x len y 0 x y nil if false c x y z z if true c xs ys z if le s c min len xs len ys s c xs ys cons sum take c xs take c ys z 2.2 addList x y le 0 min len x len y take s x cons y ys take x ys if true c xs ys z min len xs len ys len cons x xs len xs if true c xs ys z if le s c min len xs len ys s c xs ys cons sum take c xs take c ys z if true c xs ys z le s c min len xs len ys if true c xs ys z len xs sum x s y sum x y min s x s y min x y addList x y len y if true c xs ys z take c xs if true c xs ys z sum take c xs take c ys addList x y min len x len y addList x y if le 0 min len x len y 0 x y nil le s x s y le x y if true c xs ys z len ys addList x y len x if true c xs ys z take c ys true addList x y len x false addList x y if le 0 min len x len y 0 x y nil false addList x y min len x len y false if true c xs ys z if le s c min len xs len ys s c xs ys cons sum take c xs take c ys z true Failed! NaTT certifiable-1.6