createTree :: String -> Tree
createTree str = let create  = do
                                 state <- get
                                 case state of
                                 	('n':x:xs) -> do
                                 		put xs
                                 		l <- create
                                 		r <- create
                                 		return(Node x l r)
                                 	('e':xs) -> do
                                 		put xs
                                 		return Empty
                 in evalState create str