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.
n=int(raw_input())
i=1
ans=0
x=1

while 1:
    if i >n: break
    if len(str(i))==(str(i).count("0") + str(i).count("1")):
        ans+=1
    if str(i)[-1:]=="1" and n>(i+9):
        x=9
        if str(i)[-2:]=="11" and n>(i+89):
            x=89
        if str(i)[-4:]=="1111" and n>(i+8889):
            x=8889
        if str(i)[-5:]=="11111" and n>(i+88889):
            x=88889
        if str(i)[-6:]=="111111" and n>(i+888889):
            x=888889
        if str(i)[-7:]=="1111111" and n>(i+8888889):
            x=8888889
        if str(i)[-8:]=="11111111" and n>(i+88888889):
            x=88888889
    else:
        x=1
    i+=x
print ans