{-# LANGUAGE OverloadedStrings #-}
module Main where

import Prelude hiding (putStrLn, getLine, getContents)
import Data.List as L
import Data.Text as T
import Data.Text.IO

main :: IO ()
main = do
--    ln <- (read .unpack . L.head . (splitOn " ")) <$> getLine
    getLine
    ls <- T.lines <$> getContents
    putStrLn $ T.concat $ sort ls