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 -*-
def calc_r(x):
    if len(x) == 1:
        if int(x) == 0:
            return 1
        return 2
    r = calc_r(x[1:])
    if int(x[0]) == 1:
        return r + 2 ** (len(x) - 1)
    elif int(x[0]) > 1:
        return 2 ** len(x)
    else:
        return r
x = str(int(raw_input().strip()))
print calc_r(x) - 1


