# -*- Mode: Python; tab-width: 4 -*-

import coroutine
import sys

def hot_potato_1 (n):
	global co2
	while 1:
		if n == 0:
			coroutine.main ('done')
		else:
			n = coroutine.resume (co2, (n-1,))

def hot_potato_2 (n):
	global co1
	while 1:
		if n == 0:
			coroutine.main ('done')
		else:
			n = coroutine.resume (co1, (n-1,))

co1 = coroutine.new (hot_potato_1)
co2 = coroutine.new (hot_potato_2)

print coroutine.resume (co1, (int(sys.argv[1]),))