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.
s=input()
count=0
sr=''
for i in range(len(s)):
    if(s[i]=='1'):
        count+=(pow(2,(len(s)-1-i)))
        sr+='1'
    elif(s[i]=='0'):
        sr+='0'
    else:
        count+=((pow(2,(len(s)-i)))-1)
        break
print(count)
