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.

一个美丽的七月清晨，主控机（Mainframe）中发生了一件可怕的事：一个邪恶的病毒“兆字节”（Megabyte）不知怎地获得了他同样邪恶的姐姐“十六进制”（Hexadecimal）的内存访问权限。他向其中载入了大量 $ n $ 个互不相同的自然数——即从 $ 1 $ 到 $ n $ 的所有整数——以完全掌控她的能量。

但他的计划失败了。原因非常简单：十六进制只接受二进制格式表示的数字信息。这意味着，若某个十进制表示的数字中包含除 0 和 1 以外的任何字符，则该数字不会被存储在内存中。现在，兆字节想知道：成功载入的数字有多少个？

Input data contains the only number n (1 ≤ n ≤ 109).

输入数据仅包含一个数字 $n$（$1 ≤ n ≤ 10^9$）。

Output the only number — answer to the problem.

输出唯一的数字——问题的答案。

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

当 $n = 10$ 时，答案包含数字 1 和 10。