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.
def leftDigit(n):
    if 0 <= n <= 9: return n
    else: return leftDigit(n // 10)
def digitsCount(n):
    if 0 <= n <= 9: return 1
    else: return digitsCount(n // 10) + 1
def calc(n):
    if n == 0: return 1
    elif 1 <= n <= 9: return 2
    else:
        d = digitsCount(n)
        l = leftDigit(n)
        if l >= 2: return 2 ** d
        else: return 2 ** (d - 1) + calc(n - l * (10 ** (d - 1)))
    
n = input()
print( calc(n) - 1 )