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.
import math
n = int(input())
V = [1]
Vnew = [1]
i = 1
while i <= int(math.log10(n)):
    Vnewtar = []
    for j in range(len(Vnew)):
        if n >= Vnew[j]*10:
            Vnewtar.append(Vnew[j]*10)
        if n >= Vnew[j]*10 + 1:
            Vnewtar.append(Vnew[j]*10 + 1)
    Vnew = Vnewtar
    V = V + Vnew
    i += 1
print(len(V))
