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 data contains the only number $n (1 \le n \le 10^9)$.

Output the only number - answer to the problem.

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