Hexadecimal's Numbers

1000ms

65536K

Description:

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.

Sample Input:

Sample Output:

Note:

For n = 10 the answer includes numbers 1 and 10.

Informação

Provedor Codeforces

Código CF9C