Score : $200$ points
Given is an integer $N$. Find the number of positive integers less than or equal to $N$ that have an odd number of digits (in base ten without leading zeros).
Input is given from Standard Input in the following format:
$N$
Print the number of positive integers less than or equal to $N$ that have an odd number of digits.
11
9
Among the positive integers less than or equal to $11$, nine integers have an odd number of digits: $1, 2, \ldots, 9$.
136
46
In addition to $1, 2, \ldots, 9$, another $37$ integers also have an odd number of digits: $100, 101, \ldots, 136$.
100000
90909