module Main where

import Text.Printf

main :: IO ()
main = interact (show . count . bshow . read)

bshow :: Int -> String
bshow = printf "%b"

count :: String -> Int
count = foldl f 0
  where
    f 0 '0' = 0
    f 0 '1' = 1
    f n '0' = succ n
    f n '1' = succ (succ n)