rotateL :: [a] -> [a]
rotateL [] = []
rotateL (x) = last (x) : init (x)

rotateR :: [a] -> [a]
rotateR [] = []
rotateR (x) = tail(x) ++ [head (x)]

prune :: [Int] -> [Int] -> [Int]
prune (a:x) y
	| (elem a y) = prune x y
	| otherwise = a:prune x y