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
import math as mt
import bisect as bi
import collections as cc
I=lambda:list(map(int,input().split()))
input=sys.stdin.readline
cur=1
ar=[]
while 1:
	temp=int(format(cur,'b'))
	if temp>10**9:
		break
	ar.append(temp)
	cur+=1
n,=I()
print(bi.bisect(ar,n))
