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 = raw_input()
r = len(n)
if ord(n[0]) > ord('1'):
    print str(2 ** r - 1)
else:
    non1 = False
    total = 0
    for x in range(r):
        if ord(n[x]) > ord('1') or non1:
            n = n[:x] + '1' + n[x+1:]
            non1 = True
    for x in range(r):
        total += int(n[x])*(2**(r-x-1))
    print total