CF9C.Hexadecimal's Numbers

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.

Hexadecimals的数

一个美丽的七月早晨，在主机城发生了一件可怕的事情：一种恶意病毒Megabyte以某种方式获得了对他同样恶意的姐姐Hexadecimal的内存访问权限。他在那里加载了从 $1$ 到 $n$ 的 $$ 个不同自然数，以获取对她能量的完全控制。

但他的计划失败了。原因很简单：Hexadecimal除了以二进制格式写成的数字之外，不接受任何其他形式的信息。这意味着，如果十进制表示中的数字包含除0和1之外的字符，则不会存储在内存中。现在Megabyte想知道成功加载了多少个数字。

感谢Macw提供翻译

Input data contains the only number $n$ ( $1<=n<=10^{9}$ ).

输入包含一个整数$n(1 \le n \le 10^9)$。

Output the only number — answer to the problem.

输出一个整数，代表本道题的答案。

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

请注意，本题空间限制为64MB，是默认空间限制的二分之一。