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=str(int(input()))
p=len(n)
n_lst=[]
for char in n:
    if int(char)>1:
        break
    else:
        n_lst.append(int(char))
while len(n_lst)<p:
    n_lst.append(1)

ways=0
for power,dig in enumerate(n_lst):
    exp=p-power-1
    if dig==1:
        ways+=2**exp
print(ways)










        

        
