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.
"""code from gfg"""
def countNumbers(x, n):  
      
    # If number is greater than n  
    if x > n :  
        return 0
  
    # otherwise add count this number and  
    # call two functions  
    return (1 + countNumbers(x * 10, n) + 
                countNumbers(x * 10 + 1, n))  
n=int(input())
print(countNumbers(1,n))