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.
# counting binary number in decimal range
# Developed by Nazim
li=[]
i=0;
while (i<=1024):
  y=list(bin(i))
  y.pop(0)
  y.pop(0)
  k=int("".join(x for x in y))
  li.append(k) # 1 to 512 binaray is apending li list
  i+=1 

n=int(input())
if((n<1) or (n>10**9)):
    print("Input the number in correct range")
else:
    l=len(str(n))
    s=(2**(l-1))
    j=1
    count=0
    while li[s+j]<=n:    
        if(li[l+j]==n):
            j=j+1
            count=count+1
            break
        else:
            count=count+1
            j=j+1
        
    print(s+count)




