{-# OPTIONS_GHC -O2 -funbox-strict-fields #-}
import qualified Data.ByteString.Char8 as BS
import           Data.Maybe            (fromJust)

main :: IO ()
main = do
  [x, t] <- map readInt . BS.words <$> BS.getLine
  print $ solve x t

solve :: Int -> Int -> Int
solve x t = max 0 $ x - t

readInt :: BS.ByteString -> Int
readInt = fst . fromJust . BS.readInt
