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 bin_to_dec(x):
    l = []
    while x:
        l.append(x & 1)
        x >>= 1
    l = list(reversed(l))
    for i in l:
        x *= 10
        x += i
    return x

n = int(input())
ans = 0

for i in range(1, 1 << 10):
    if (bin_to_dec(i) <= n):
        ans += 1
    else:
        break

print(ans)
