import Control.Monad
import Control.Applicative
import Data.List

-- String, Int, Char, IO
-- putStrLn
-- e.g.
-- 1
-- [a] <- map read . words <$> getLine => [1] -> a == 1
-- 1
-- a <- readLn
-- 1 2 3
-- lst <- map read . words <$> getLine => [1, 2, 3]
-- 1 2 3
-- [l, m, n] <- map read . words <$. getLine :: IO [Int] => [1, 2, 3]
-- 'a'
-- c <- getChar => c == 'a'
--
-- slst <- replicateM h getLine


getBysplit = map read . words <$> getLine

main :: IO()
main = do
  [x, t] <-  getBysplit :: IO [Int]
  let ans = if x - t > 0
              then x -t
              else 0
  print ans
