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.
#!/usr/bin
def load_success(num, a=10):
    b_nums, ans = [0, 1], 1
    while(True):
        temp = []
        for t in b_nums:
            if num >= (a + t):
                ans = -~ans
                temp.append(a+t)
                continue
            return ans
        a = ( a << 3 ) + (a << 1)
        b_nums.extend(temp)

print load_success(int(raw_input()))