import qualified Data.ByteString.Char8 as B
import Data.List

wd = '|'

main = do
 getLine
 bs <- map (flip B.snoc wd) . B.lines <$> B.getContents
 putStrLn (merge bs)

merge bs = reverse $ fst $ until (null . snd) conc ("", sort bs)

conc (r,(b:bs)) = (c:r, sort (filter notNull (b':bs)))
 where
  (Just (c,b')) = B.uncons b
  notNull = not . (== wd) . B.head