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.
n = input()
def approx(n):
    d = '1'
    for i in range(1,len(n)):
        if (d+'1'+'0'*(len(n)-i-1)) <= n:
            d = d+'1'
        else:
            d = d+'0'
    return d

def btd(s):
    su = 0
    exp = len(s)-1
    for d in s:
        su += int(d)*(2**exp)
        exp += -1
    return su

print(btd(approx(n)))
