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.
import sys,math,bisect
inf = float('inf')
mod = (inf)+7

"=========================="
def lcm(a,b):
    return int((a/math.gcd(a,b))*b)
def gcd(a,b):
    return int(math.gcd(a,b))
def binarySearch(a,x):
    i = bisect.bisect_left(a,x)
    if i!=len(a) and a[i]==x:
        return i
    else:
        return -1
def lowerBound(a, x):
    i = bisect.bisect_left(a, x)
    if i:
        return (i-1)
    else:
        return -1
def upperBound(a,x):
    i = bisect.bisect_right(a,x)
    if i!= len(a)+1 and a[i-1]==x:
        return (i-1)
    else:
        return -1
def SieveOfEratosthenes(n):
    ans = []
    prime = [True for i in range(n+1)]
    p = 2
    while (p * p <= n):
        if (prime[p] == True):
            for i in range(p * p, n+1, p):
                prime[i] = False
        p += 1
    for p in range(2, n+1):
        if prime[p]:
            ans.append(p)
    return ans
"============================"
"""
n = int(input())
n,k = map(int,input().split())
arr = list(map(int,input().split()))
"""


for _ in range(1):
    cnt = 0
    n=int(input())
    i=1
    while int(bin(i)[2:]) <=n:
        cnt+=1
        i+=1
    print(cnt)
