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 re

def count(numStr, numStrLen, i):
    if numStr[i] != '0' and numStr[i] != '1':
        return 2 ** (numStrLen - i) - 1
    if i == numStrLen - 1:
        if numStr[i] == '0':
            return 0
        return 1

    if numStr[i] == '1':
        return 2 ** (numStrLen - i - 1) + count(numStr, numStrLen, i + 1)
        
    if numStr[i] == '0':
        return count(numStr, numStrLen, i + 1)

def main():
    numStr = raw_input()
    l = len(numStr)
    print count(numStr, l, 0)

if __name__ == '__main__':
    main()




