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 sys
import math

n = int(sys.stdin.readline())

k = [1]

t = 10
res = 1
for i in range(9):
    v = [t]
    if(n >= t):
        res += 1
    for j in k:
        v.append(j + t)
        if(n >= t + j):
            res += 1
    t *= 10
    k.extend(v)
 
   
print(res)
        