import Prelude

main :: IO ()
main = do
  n <- read <$> getLine
  print $ calc n

calc :: Int -> Int
calc 1                = 0
calc n | mod n 2 == 1 = 1 + calc' (n - 1)
       | otherwise    = calc' n
  where
    calc' :: Int -> Int -- n is always even.
    calc' n = let ms = takeWhile (<= n) $ iterate (* 2) 1
              in  if last ms == n then length ms - 1
                                  else length ms