-- https://wiki.c2.com/?OddWordProblem (pointless)

import Data.List
import Control.Monad

split :: [a] -> ([a], [a])
split xs = (g even, g odd)
  where g f = map fst $ filter (f . snd) $ zip xs [0..]

merge :: [a] -> [a] -> [a]
merge xs ys = concat $ transpose [xs, ys]

oddWords :: [String] -> [String]
oddWords w = let (e, o) = split w in merge e (map reverse o)

main = (interact $ unwords . oddWords . words) >> putStrLn "."