Count Digit Occurrences

Problem Background

Corresponding multiple-choice / true-false question: https://ti.luogu.com.cn/problemset/1150

Problem Description

Xiao Yang believes his lucky number is the positive integer $k$ (it is guaranteed that $1 \le k \le 9$). Xiao Yang wants to know how many times $k$ appears among all positive integers from $1$ to $n$.

Input Format

The first line contains a positive integer $n$.

The second line contains a positive integer $k$.

Output Format

Output the number of times $k$ appears among all positive integers from $1$ to $n$.

Sample Input

25
2

Sample Output

9

Sample Explanation

From $1$ to $25$, the positive integers in which $2$ appears are $2, 12, 20, 21, 22, 23, 24, 25$, for a total of $9$ occurrences.

Constraints

For all test data, it is guaranteed that $1 \le n \le 1000$ and $1 \le k \le 9$.