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 binaryToDecimal(n): 
    num = n; 
    dec_value = 0; 
    base = 1; 
    temp = num; 
    while(temp): 
        last_digit = temp % 10; 
        temp = int(temp / 10); 
        dec_value += last_digit * base; 
        base = base * 2; 
    return dec_value;

n=int(input())
cn=0
li=[]
while n!=0:
    cn+=1
    li.append(n%10)
    n//=10
li.reverse()
mind=len(li)
for i in range(len(li)):
    if li[i]>1:
        mind=i
        break
    li[i]=str(li[i])
for i in range(mind,len(li)):
    li[i]=1
    li[i]=str(li[i])
print(binaryToDecimal(int("".join(li))))
