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 mi():return map(int,input().split())
def li():return list(mi())
def ii():return int(input())
def si():return input()
s1=si()
n=len(s1)
s1=int(s1)
ans=0
for i in range(n-1,0,-1):
    ans+=pow(2,i-1)
b=[]
for i in range(pow(2,n-1)):
    s=bin(i)
    s=s[2:]
    x=n-1-len(s)
    s='0'*x+s
    b.append(pow(10,n-1)+int(s))
for i in b:
    if(i<=s1):
        ans+=1
print(ans)