import Control.Monad
import Control.Applicative
import Data.List

main :: IO()
main = do
  s <- getLine
  putStrLn $ oddString s


oddString :: String -> String
oddString s = f [] s True
    where
      f :: String -> String-> Bool -> String
      f acc   []    _    = reverse acc
      f acc (x:xs) True  = f (x:acc) xs False
      f acc (x:xs) False = f acc xs True
