module Main where

data Tree a = Empty | Node a (Tree a) (Tree a) deriving (Show)

inOrder :: Tree a -> [a]
inOrder Empty = []
inOrder (Node a left right) = inOrder left ++ [a] ++ inOrder right

insertNode :: (Ord a) => Tree a -> a -> Tree a
insertNode Empty x = Node x Empty Empty
insertNode (Node a left right) x
    | x < a = Node a (insertNode left x) right
    | x > a = Node a left (insertNode right x)
    | otherwise = Node a left right

height :: Tree a -> Int
height Empty = 0
height (Node _ Empty Empty) = 0
height (Node _ left right) = 1 + max (height left) (height right)

main :: IO ()
main = do
    _ <- getLine
    xs <- fmap (map read . words) getLine :: IO [Int]
    let tree = foldl insertNode Empty xs
    print $ height tree