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())
k=1
z=1
s=1
if n<10 :
    print(1)
    exit()
for i in range(1,len(str(n))-1) :
    z*=2
    k+=z
    
    
    
n=str(n)
d=0

if int(n[0])>1 :
        d=1
for i in range(1,len(n)) :
    if int(n[i])>1 :
        d=1
    if n[i]!='0' or d==1 :
        k+=2**(len(n)-i-1)
        
        
        
print(k+1)
