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.
import sys
from itertools import product

file = sys.stdin
num = int(file.readline().rstrip())

d = [0, 1]
for lenth in range(1, 10):
    p = map(lambda t : int("1" + "".join(t)), product(['0', '1'], repeat=lenth));
    p.sort()
    d += p
for i in range(len(d)):
    if d[i] > num:
        break

print i - 1
