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.
from sys import stdin,stdout
import bisect as bs
nmbr=lambda:int(stdin.readline())
lst = lambda: list(map(int,input().split()))
def binary(mask):
    s=0
    for i in range(64,-1,-1):
        if (mask>>i)&1:s=s*10+1
        else:s=s*10
    return s

for _ in range(1):#nmbr()):
    n=nmbr()
    a=[]
    for mask in range(1,1<<10+1):
        a+=[binary(mask)]
    p=bs.bisect_left(a,n)
    if a[p]!=n:p-=1
    print(p+1)