Problem Statement

Given is an integer $N$. How many integers $x$ between $1$ and $N$ (inclusive) satisfy the following condition?

• The decimal representation (without leading zeros) of $x$ has an even number of digits, and its first and second halves are equal as strings.

Constraints

• $N$ is an integer.
• $1 ≤ N < 10^{12}$

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.