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())
i = 1
def bin_notation(n):
    ans = ''
    while(n>0):
        ans += str(n%2)
        n = n//2
    ans = ans[::-1]
    return int(ans)
val = list()
while i<=1025:
    val.append(bin_notation(i))
    i += 1
ans = 0
for ele in val:
    if ele > n:
        break
    ans += 1
print(ans)