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 tobin(i):
    if i == 0: return 0
    r = ""
    while i > 0:
        r = str(i % 2) + r
        i /= 2
    return int(r, 10)


def calc(n):
    i = 1
    #print "\n check", tobin(i)
    #print type(n), type(tobin(i)), n >= tobin(i)
    while n >= tobin(i):
        i += 1
    return i-1

#for x in range(13):
#    print x, tobin(x), calc(x)

n = int(raw_input())
print calc(n)    
