Problem Description

There is a row of $n$ bottles of orange juice, where the brand of the $i$-th bottle is $a_i$.

You may spend a cost of $1$ unit to swap two adjacent bottles of orange juice.

Find the minimum cost to make the leftmost $k$ bottles have pairwise distinct brands.

Input Format

The first line contains two integers $n, k$.

The second line contains $n$ integers $a_1, a_2, \cdots, a_n$.

Output Format

Output one integer in one line: if a solution exists, output the minimum cost; otherwise, output $-1$.

5 3
3 3 3 1 2

4

3 2
1 1 1

-1

Hint

Sample #1 Explanation

The optimal plan is to first swap the bottles at positions $3$ and $4$, then swap the bottles at positions $4$ and $5$, then swap the bottles at positions $2$ and $3$, and finally swap the bottles at positions $3$ and $4$, for a total of $4$ operations.

Sample #2 Explanation

Clearly, there is no solution.

Constraints

For $100\%$ of the testdata, $1 \leq k, a_i \leq n \leq 5 \times 10^5$.

Translated by ChatGPT 5