614. Sum of Numbers With Units Digit K

0

Medium

Given two integers num and k, find the minimum possible size of a set of positive integers that satisfies the following conditions: 1. The units digit of each integer in the set is k. 2. The sum of all integers in the set is equal to num. If no such set exists, output -1. Note: - The set can contain multiple instances of the same integer. - The sum of an empty set is considered 0. - The units digit of a number refers to the rightmost digit of the number.

Input Format

The input consists of two lines: - The first line contains the value of num. - The second line contains the value of k.

Output Format

Output a single integer, which represents the minimum possible size of a valid set. If no such set exists, output -1.

Example

Input

58 9

Output

2

Constraints

0 <= num <= 3000
0 <= k <= 9
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