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.
def itoa(x, base) :
    negative = False
    s = ""
    if (x == 0) :
        return "0"
    negative = (x < 0)
    if (negative) :
        x = -1 * x
    while (x != 0) :
        s = str(x % base) + s 
        x = int(x / base) 
     
    if (negative) :
        s = "-" . s
 
    return s
 
def binaryGenerator(n,uplim) :
    numofnum=0
    for i in range(1, n + 1) :
        numofnum+=1
        i+=1
        if(int(itoa(i,2))>uplim):
           break
    return numofnum
uplimstr=input()    
uplim=int(uplimstr)
n = 2**len(uplimstr)
print(binaryGenerator(n,uplim))