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())
cnt = 0
acc = ['1']
prev_lvl = ['1']
for i in range(len(str(n))-1):
    new_batch = []
    for s in prev_lvl:
        new_batch.append(s + '0')
        new_batch.append(s + '1')
    acc.extend(new_batch)
    prev_lvl = new_batch

sol = [potential for potential in acc if int(potential) <= n]
# print(sol)
print(len(sol))
