import Control.Applicative ((<$>))
import Data.List

import Text.Printf

main :: IO ()
main = do
  solve <$> getl (map read . words) >>= printf "%.2f\n"

solve :: [Int] -> Double
solve ss = let mx = maximum ss
               mn = minimum ss
           in fromIntegral (sum (delete mn (delete mx ss))) / 4.0

getl :: (String -> a) -> IO a
getl f = f <$> getLine