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 data contains the only number *n* (1 ≤ *n* ≤ 10<sup class="upper-index">9</sup>).
For *n* = 10 the answer includes numbers 1 and 10.
10
2
20
3
72
3
99
3
100
4
101
5
102
5
111
7
112
7
745
7
23536
31
1
1
1010011
83
312410141
511
1000000000
512
999999999
511
111111111
511
101010101
341
121212121
511
106341103
383
901556123
511
832513432
511
3
1
732875234
511
7
1
9
1
2
1
11
3
12
3
13
3
101020101
351
111100100
484
110110101
437
100111001
313
100100
36
110100102
421
import itertools

import time
def timer(f):
    def tmp(*args, **kwargs):
        t = time.time()
        res = f(*args, **kwargs)
        print("Время выполнения функции: %f" % (time.time()-t))
        return res

    return tmp

#n = int(input())

def realAle(string):
    string = string.lstrip('0')
    if len(string)==0:
        return 1
    if string == "1":
        return 2
    if int(string[0])>1:
        return 2**len(string)
    else:
        return (2**(len(string)-1))+realAle(string[1:])



def real(string):
    string = string.lstrip('0')
    if len(string)==0:
        return 1
    if string == "1":
        return 1
    if int(string[0])>1:
        return 2**len(string)-1
    else:
        return (2**(len(string)-1))-1+realAle(string[1:])



def naive(k):
    count = 0
    for i in range(1, k+1):
        s = str(i)
        b = True
        for j in range(len(s)):
            if s[j]!='0' and s[j]!='1':
                b = False
        if b:
            #print(i)
            count+=1
    return count


for i in range(1, 1):
    if naive(i)!=real(str(i)):
        print(i,  naive(i), real(str(i)) )
        pass

print(real(input()))