{-# LANGUAGE BangPatterns          #-}

import Control.Monad
import Control.Applicative
import Data.List as List
import Data.Set as Set



solve:: Int -> String -> String
solve _ [] = ""
solve i (x:xs)
    | (mod i 2) == 0 = solve (i + 1) xs
    | otherwise = [x] ++ (solve (i + 1) xs) 

main :: IO()
main = do
    s <- getLine
    let a = solve 1 s
    putStrLn a
