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.
#!/usr/bin/env python

def convert(n):
    bStr = ''
    if n == 0: return '0'
    while n > 0:
        bStr = str(n % 2) + bStr
        n = n >> 1
    return int(bStr)

n = int(raw_input())

result = 0
for i in range(1, 513):
	if convert(i) <= n:
		result += 1

print result
