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 math import inf as inf
from math import *
from collections import *
import sys
input=sys.stdin.readline
t=1
while(t):
    t-=1
    n=int(input())
    s=0
    for i in range(1,2**9+1):
        x=bin(i)[2:]
        if(int(x)>=1 and int(x)<=n):
            s+=1
    print(s)
