#処理内容
def main():
	N = int(input())
	ans = 0
	for i in range(10, 100):
		if i % 3 == 0 and i <= N:
			ans += 1

	for i in range(4 ** 9):
		num = ""
		n = i
		for j in range(9):
			num += str(3 * (n % 4))
			n //= 4

		num = int(num)
		if 100 <= num <= N:
			ans += 1

	print(ans)

if __name__ == '__main__':
	main()