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 perm(s,all_pos):
    a = s*10
    b = a+1
    all_pos+=[a,b]
    if(a<(10**9)):
        perm(a,all_pos)
    if(b<10**9):
        perm(b,all_pos)
def prog():
    all_pos=[1]
    perm(1,all_pos)
    all_pos.sort()
    n = input()
    for i in xrange(0,len(all_pos)):
        if(all_pos[i]>n):
            print i
            break
prog()
