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.
a=int(input())
d=str(a)
b=len(d)
e=1;
if(a<10):
    print(1)
else:
    if(int(d[0])==1):
        for i in range(b):
            if(int(d[i])==1):
                e=e+pow(2,b-i-1)
            if(int(d[i])>1):
                e=e+pow(2,b-i)-1
                break
        print(e-1);
    if(int(d[0])>1):
        f=pow(2,b)
        print(f-1)