module Main (main) where

import qualified Data.ByteString.Char8     as C8
import           Data.Maybe

main :: IO ()
main = do
  [x,t] <- readInts
  putStrLn $ pretty $ solve (x,t)

type Input  = (Int, Int)
type Output = Int

solve :: Input -> Output
solve (x,t) = if y < 0 then 0 else y
  where
    y = x-t

pretty :: Output -> String
pretty = show

-- utils
readInts :: IO [Int]
readInts = map (fst . fromJust . C8.readInt) . C8.words <$> C8.getLine