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

def dig(n):
    
    cnt=0
    while(n>0):
        
        cnt=cnt+1
        n=n/10
        
        
    return cnt
    
    

n=int(raw_input())
ans = 0
while(n>0):
    p=0
    for i in range(0,dig(n)):
        p=p*10+1;
        
    if(n>=p):
        
        ans = ans + pow(2,dig(n))-1
        n=0;
        
    else:
        
        ans = ans + pow(2,dig(n)-1)
        n=n-pow(10,dig(n)-1)
        
    
    
    
print ans
