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.
x = raw_input()
x = list(x)
for i in range(0, len(x)):
    x[i] = int(x[i])

for i in range(0, len(x)):
    if x[i] > 1:        
        for j in range(i, len(x)):
            x[j] = 1
        break

ans = 0
for i in range(0, len(x)):
    ans = ans * 2 + x[i]

print ans
print '\n'
       
    
