One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
def get_all_binaries(digits):
	all_binaries = set()
	def generate_binary(digits, idx = 0):
		if idx == len(digits):
			number = int(''.join(digits))
			# print(number)
			all_binaries.add(number)
			return
		generate_binary(digits, idx+1)
		digits[idx] = '1'
		generate_binary(digits, idx+1)
		digits[idx] = '0'
		return
	generate_binary(digits)
	return all_binaries

if __name__ == '__main__':
	n = int(input())
	digits = ['0' for i in range(10)]
	binaries = get_all_binaries(digits)
	ans = 0
	binaries = sorted(binaries)	
	for i in binaries:
		if i <= n and i > 0:
			# print(i)
			ans += 1

	# print(binaries)
	print(ans)