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
n = input().strip()

if int(n[0]) > 1:
    print( 2 ** len(n) - 1 )
else:
    lenn = len(n)
    x = 2 ** (lenn-1) - 1
    for i in range(1, lenn):
        if int(n[i]) > 1:
            x += 2 ** (lenn - i)
            print(x)
            sys.exit(0)
        elif int(n[i]) == 1:
            x += 2 ** (lenn - 1 - i)
        else:
            continue
    print(x+1)
