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 collections import defaultdict
n=input()
l=len(n)
graph={"0":["0","1"],"1":["0","1"]}
ans=set()
def dfs(s,m):
    s+=m
    if len(s)==l:
        if int(s)<=int(n) and int(s)!=0:
            ans.add(int(s))
    elif len(s)>l:
        return
    for i in graph[m]:
        dfs(s[:],i)
s=""
for i in graph:
    dfs(s[:],i)
print(len(ans))