X = int(input())
i = 0
ans = 0
while True:
	i += 2
	ans += 2
	if i == X:
		print(ans)
		exit()
	i += 2
	ans += 2
	if i == X:
		print(ans)
		exit()
	i -= 1
	ans += 1
	if i == X:
		print(ans)
		exit()
	i -= 1
	ans += 1
	if i == X:
		print(ans)
		exit()
	i += 2
	ans += 2
	if i == X:
		print(ans)
		exit()
	i -= 1
	ans += 1
	if i == X:
		print(ans)
		exit()
	i -= 1
	ans += 1
	if i == X:
		print(ans)
		exit()