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.
__author__ = 'Will'


values = raw_input()
count = 0


bin = 2**len(values) #binary value of values
for i in values:
    if i =='1': #if x is 1, it's correct, divide and add our bin to count
        bin/=2
        count += bin
    elif i == '0':  #if x is 0, divide our bin, it's correct, don't add since it's 0
        bin/= 2
    else:
        count += bin-1 #it's a corrupted value, nothing from here is read, but we'll add last related count
        break #knowing that this value is corrupted we subtract 1

print count