output_description: Print the number of sand in the upper bulb after t second.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      X t
attempt: #!usr/bin/env python3
  from collections import defaultdict
  from collections import deque
  from heapq import heappush, heappop
  import sys
  import math
  import bisect
  import random
  import itertools
  
  sys.setrecursionlimit(10**5)
  stdin = sys.stdin
  
  
  def LI():
      return list(map(int, stdin.readline().split()))
  
  
  def LF():
      return list(map(float, stdin.readline().split()))
  
  
  def LI_():
      return list(map(lambda x: int(x) - 1, stdin.readline().split()))
  
  
  def II():
      return int(stdin.readline())
  
  
  def IF():
      return float(stdin.readline())
  
  
  def LS():
      return list(map(list, stdin.readline().split()))
  
  
  def S():
      return list(stdin.readline().rstrip())
  
  
  def IR(n):
      return [II() for _ in range(n)]
  
  
  def LIR(n):
      return [LI() for _ in range(n)]
  
  
  def FR(n):
      return [IF() for _ in range(n)]
  
  
  def LFR(n):
      return [LI() for _ in range(n)]
  
  
  def LIR_(n):
      return [LI_() for _ in range(n)]
  
  
  def SR(n):
      return [S() for _ in range(n)]
  
  
  def LSR(n):
      return [LS() for _ in range(n)]
  
  
  mod = 1000000007
  
  
  # A
  def A():
      x, t = LI()
      print(max(0, x - t))
  
      return
  
  
  # B
  def B():
      return
  
  
  # C
  def C():
      return
  
  
  # D
  def D():
      return
  
  
  # E
  def E():
      return
  
  
  # F
  def F():
      return
  
  
  # G
  def G():
      return
  
  
  # H
  def H():
      return
  
  
  # Solve
  if __name__ == "__main__":
      A()
  
problem_description: Statement
  
  We have a sandglass that runs for X seconds. The sand drops from the upper
  bulb at a rate of 1 gram per second. That is, the upper bulb initially
  contains X grams of sand.
  
  How many grams of sand will the upper bulb contains after t seconds?
samples: [{"input": "100 17", "output": "83\n    \n\n17 out of the initial 100 grams of sand will be consumed, resulting in 83\ngrams.\n\n* * *"}, {"input": "48 58", "output": "0\n    \n\nAll 48 grams of sand will be gone, resulting in 0 grams.\n\n* * *"}, {"input": "1000000000 1000000000", "output": "0"}]