old_contents: import sys
  
  def ack(m, n):
      if (not m):
  	return n + 1
      if (not n):
  	return ack(m - 1, 1)
      return ack(m - 1, ack(m, n - 1))
  
  def main():
      n = int(sys.argv[1])
      sys.setrecursionlimit(10000)
      print "Ack(3, %d) = %d" % (n, ack(3, n))
  
  main()
  
new_contents: import sys
  
  def ack(m, n):
      if (not m):
  	return n + 1
      if (not n):
  	return ack(m - 1, 1)
      return ack(m - 1, ack(m, n - 1))
  
  def main():
      n = int(sys.argv[1])
      sys.setrecursionlimit(100000)
      print "Ack(3, %d) = %d" % (n, ack(3, n))
  
  main()
  
subject: increase ack.py recursion limit, so that python runs ack(3,11) - +4 times slower than parrot ;)