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.
'''
Author:
Fuad Ashraful Mehmet
University of Asia Pacific
date :28 Jan Dec T20
Category:bfs+ds
'''

class Virus:
    def __init__(self,n):
        self.n=n
        self.queue=[]
        self.cnt=0
    
    def Solve(self):
        self.queue.append(1)
        while len(self.queue):
            tp=self.queue.pop()
            self.cnt+=1
            if tp*10<=self.n:
                self.queue.append(tp*10)
            if tp*10+1<=self.n:
                self.queue.append(tp*10+1)

        return self.cnt

obj=Virus(int(input()))

print(obj.Solve())