{-# LANGUAGE BangPatterns #-}

import Data.List (sort)

main :: IO ()
main = do
  getLine
  vs <- sort . map read . words <$> getLine
  print $ solve vs

solve :: [Double] -> Double
solve (v:vs) = go v vs
  where
    go !acc []     = acc
    go !acc (v:vs) = go ((acc + v) / 2.0) vs