text: # Ackermann's function
  
  def ackermann (m, n):
     if m == 0: 
        return n+1
     if m > 0 and n == 0:
        return ackermann (m-1, 1)
     if m > 0 and n > 0: 
        return ackermann (m-1, ackermann (m, n-1))
  
  print (ackermann (3,4))
  
  print (ackermann (4,0))
  