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.
#!/usr/bin/env python
# -*- coding: UTF-8 -*-
import time
import sys, io
import re, math
start = time.clock()
n=int(raw_input())
i=1
ans=0
x=1
#どうしたらいいかわからなかったらとりあえずwhile 1:ループ
while 1:
#数え上げが上限のnをこえたら終了
    if i >n: break
#strにキャストして文字数(桁数)と1,0の個数の和が等しければ1,0のみで構成かな？
    if len(str(i))==(str(i).count("0") + str(i).count("1")):
        ans+=1
#下桁が1並びでないかチェックして並びに応じて一気に加算
    if str(i)[-1:]=="1":
        x=9
        if str(i)[-2:]=="11":
            x=89
        if str(i)[-4:]=="1111":
            x=8889
        if str(i)[-5:]=="11111":
            x=88889
        if str(i)[-6:]=="111111":
            x=888889
        if str(i)[-7:]=="1111111":
            x=8888889
        if str(i)[-8:]=="11111111":
            x=88888889
    else:
        x=1
    i+=x
print ans