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.
# -*- coding: utf - 8 -*-
"""""""""""""""""""""""""""""""""""""""""""""
|    author: mr.math - Hakimov Rahimjon     |
|    e-mail: mr.math0777@gmail.com          |
|    created: 27.01.2018 10:05              |
"""""""""""""""""""""""""""""""""""""""""""""
# inp = open("input.txt", "r"); input = inp.readline; out = open("output.txt", "w"); print = out.write
TN = 1


# ===========================================


def solution():
    n = int(input())
    ans = 1
    for i in range(2,1024):
        if int(bin(i)[2:])>n: break
        else: ans+=1
    print(ans)


# ===========================================
while TN != 0:
    solution()
    TN -= 1
# ===========================================
# inp.close()
# out.close()
