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(input())

maximum = pow(2, 10)

best = 0
total = 0 

for i in range(1, maximum):
    num = "{0:b}".format(i)
    intnum = int(num)
    if intnum <= n :
        best = intnum 
        continue 
    break 

if best == 0 or best == 1:
    print(best)
else:
    strs = str(best)
    getLen = len(strs) - 1 
    #print(strs)
    #print("inside")
    for i in strs:
        if i == '1' :
            total += pow(2, getLen)
        getLen -= 1 

    print(total)