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.
def get_binary(num):
    """
    this function gets the maximum binary number
    from 1 to num
    """
    flag = False
    binary = ''
    for char in num:
        if(int(char) > 1):
            flag = True
        if flag:
            binary += '1'
        else:
            binary += char
            
    return binary

def main():

    n = str(input())    
    binary = get_binary(n)
    print(int(binary, 2))


    
if __name__ == '__main__':
    main()
