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 g(n,base):
    convertString = "0123456789ABCDEF"
    if n < base:
        return convertString[n]
    else:
        return g(n//base,base) + convertString[n%base]
def f(n):
    s = []
    for i in xrange(1, 2**10):
        s.append(g(i, 2))
    s = sorted(map(int, filter(lambda x:x[0] != '0', s)))
    return len(filter(lambda x: x <= n, s))
print f(int(raw_input()))