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 digs(n):
    d = 0
    while n > 0:
        d += 1
        n = n // 10
    return d
def leftDig(n):
    while n >= 10:
        n = n // 10
    return n

def cou(n):
    if 0 == n: return 1
    elif 1 <= n <= 9: return 2
    else:
        d = digs(n)
        l = leftDig(n)
        if l == 1: 
            return (2 ** (d - 1)) + cou(n - leftDig(n) * (10 ** (d - 1)))
        else:
            return 2 ** d;

a = input()
b = cou(a)
b = b - 1
print (b)