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 calc(s):
    return int(''.join(s))
def count(s,ind,c):
    global co
    if ind==len(s):
        k= calc(c)
        if calc(c)<=int(s) and k!=0 :
            co+=1
        return 
    else:
        c[ind]='1'
        count(s,ind+1,c)
        c[ind]='0'
        count(s,ind+1,c)

n = int(input())
co = 0
s =  str(n)
c = ['0']*(len(s))
count(s,0,c)
print(co)