Eval is useful to do operation.```#!/usr/bin/pythonfrom pwn import *p = connect("chals20.cybercastors.com",14429)print p.recv()p.send('\n')while True:	data = p.recv().split(' ')	print data	one,two,three,four,five,six,seven,eight,nine=1,2,3,4,5,6,7,8,9	if data[3] == "minus":		data[3] = "-"	if data[3] == "plus":		data[3] = "+"	if data[3] == "divided-by":		data[3] = "//"	if data[3] == "multiplied-by":		data[3] = "*"	result = eval(str(data[2])+data[3]+str(data[4]))	print result	p.send(str(result))	print p.recv()```