#!/usr/bin/python

import sys

class MyPythonclass:
	def __init__(self):
		print "Hello"
	def process:
		print "Select: \n"
		print "1.Add\n2.Subtract\n3.Multiplication\n4.Division\n"
		vr=raw_input()
		if vr==1:
			add(5,9)
		elif vr==2:
			subt(9,5)
		elif vr==3:
			mult(5,9)
		else vr==4:
			div(4,2)

	def add(self,a,b):
		return a+b
	def subt(self,a,b):
		return a-b
	def mult(self,a,b):
		return a*b
	def div(self,a,b):
		if b!=0:
			return a/b
		elif b==0:
			return "Divide by zero error."

obj=MyPythonclass()
while 1>0:
	obj.process