import Control.Applicative
import Data.List

main :: IO ()
main = do
  n <- read <$> getLine
  a <- map read . words <$> getLine
  putStrLn $ show $ solve n a

solve :: Int -> [Double] -> Double
solve n a
  | odd n = head $ drop (n `div` 2) (sort a)
  | otherwise =
    let rs = drop ((n `div` 2) - 1) $ sort a
    in (rs !! 0 + rs !! 1) / 2