import Control.Monad
import Control.Monad.ST
import Data.Char
import Data.List
import qualified Data.ByteString.Char8 as B
import qualified Data.Vector.Unboxed as V
import qualified Data.Vector.Unboxed.Mutable as MV

main = B.interact$B.pack.show.f.unfoldr(B.readInt.B.dropWhile isSpace)
f (n:ps) = sum pp + (p `div` 2)
    where
        (p:pp)=reverse $ sort ps