makeBST :: Ord a => [a] -> BST a
makeBST l= aux (sort l)

aux []= BSTNil
aux l =BSTNod mij (aux st) (aux dr) where
	lung = length l
	mij = l !! (div lung 2)
	st = take (div lung 2) l
	dr = drop ((div lung 2)+ 1) l

findElem :: (Ord a, Eq a) => a -> BST a -> Maybe a
findElem _ BSTNil = Nothing
findElem x (BSTNod y st dr)
	| x == y = Just x
	| x < y = findElem x st
	| otherwise = findElem x dr

inorder :: BST a -> [a]
inorder BSTNil = []
inorder (BSTNod x st dr) = (inorder st) ++ [x] ++ (inorder dr)