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.
n = int(input())

s = set()

def rec(num):
    global s
    if len(num) == 10:
        s.add(num)
        return
    else:
        s.add(num)
    rec(num + '1')
    rec(num + '0')

rec('0')
rec('1')

nums = set()

for i in s:
    nums.add(int(i))

nums = list(nums)

nums.sort()

nums = nums[1:]

ans = 0

for i in nums:
    if i > n:
        break
    ans += 1

print(ans)
