import Data.List (sort)
import Data.Functor ((<$>))

median [x] = x
median [x,y] = (x+y)/2.0
median xs = median $ droplast $ tail xs where
  droplast [x] = []
  droplast (x:xs') = x:droplast xs'

main = do
  getLine
  show . median . map fromIntegral . sort . map read . words <$> getLine >>= putStrLn