import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe (fromJust)
import Text.Printf
import Debug.Trace

main = do
  [w,a',b'] <- getInts
  let (a,b) = (min a' b', max a' b')
  print $ if b <= a+w then 0
          else b - a - w

-- util
getInts :: IO [Int]
getInts = map (fst . fromJust . B.readInt) . B.words <$> B.getLine
