27569번 - Champernowne Count 다국어

The $n$th Champernowne word is obtained by writing down the first $n$ positive integers and concatenating them together. For example, the 10th Champernowne word is "12345678910".

Given two positive integers $n$ and $k$, count how many of the first $n$ Champernowne words are divisible by $k$.

The single line of input contains two integers, $n$ $(1 \le n \le 10^5)$ and $k$ $(1 \le k \le 10^9)$.

Output a single integer, which is a count of the first $n$ Champernowne words divisible by $k$.