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())
m=n
yo=[]
while(m!=0):
    yo.append(m%10)
    m//=10
i=len(yo)-1
while(yo[i]<=1 and i>=0):
    i-=1
while(i>=0):
    yo[i]=1
    i-=1
p=1
ans=0
for i in yo:
    ans+=p*i
    p*=2
print(ans)