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 math
def toString(x):
    ans =""
    while(x):
        if x%2==0:
            ans+="0"
        else:
            ans+="1"
        x/=2
    ans+="0"
    return ans[::-1]
n = input()
count = 0
for i in range(1,2**int(math.ceil(math.log(n)))+1):
    s = toString(i)
    if n>= int(s):
        count+=1
    else:
        break

print count
