import Data.List
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = breads >>= print . solve

solve :: [Int] -> Int
solve xs = fst $ foldl' ff (0, y) ys
    where
        (y : ys) = sort xs
        ff (acc, a) b = (acc + b - a, b)

breads :: IO [Int]
breads = unfoldr uff <$> B.getLine
    where
        uff b = check <$> B.readInt b
        check (a, b)
            | B.null b = (a, b)
            | otherwise = (a, B.tail b)