#P1823B. Sort with Step

Sort with Step

No submission language available for this problem.

Description

Let's define a permutation of length nn as an array pp of length nn, which contains every number from 11 to nn exactly once.

You are given a permutation p1,p2,,pnp_1, p_2, \dots, p_n and a number kk. You need to sort this permutation in the ascending order. In order to do it, you can repeat the following operation any number of times (possibly, zero):

  • pick two elements of the permutation pip_i and pjp_j such that ij=k|i - j| = k, and swap them.

Unfortunately, some permutations can't be sorted with some fixed numbers kk. For example, it's impossible to sort [2,4,3,1][2, 4, 3, 1] with k=2k = 2.

That's why, before starting the sorting, you can make at most one preliminary exchange:

  • choose any pair pip_i and pjp_j and swap them.

Your task is to:

  1. check whether is it possible to sort the permutation without any preliminary exchanges,
  2. if it's not, check, whether is it possible to sort the permutation using exactly one preliminary exchange.

For example, if k=2k = 2 and permutation is [2,4,3,1][2, 4, 3, 1], then you can make a preliminary exchange of p1p_1 and p4p_4, which will produce permutation [1,4,3,2][1, 4, 3, 2], which is possible to sort with given kk.

Each test contains multiple test cases. The first line contains the number of test cases tt (1t1041 \le t \le 10^4). The description of the test cases follows.

The first line of each test case contains two integers nn and kk (2n21052 \le n \le 2 \cdot 10^5; 1kn11 \le k \le n - 1) — length of the permutation, and a distance between elements that can be swapped.

The second line of each test case contains nn integers p1,p2,,pnp_1, p_2, \dots, p_n (1pin1 \le p_i \le n) — elements of the permutation pp.

It is guaranteed that the sum of nn over all test cases does not exceed 21052 \cdot 10 ^ 5.

For each test case print

  • 0, if it is possible to sort the permutation without preliminary exchange;
  • 1, if it is possible to sort the permutation with one preliminary exchange, but not possible without preliminary exchange;
  • -1, if it is not possible to sort the permutation with at most one preliminary exchange.

Input

Each test contains multiple test cases. The first line contains the number of test cases tt (1t1041 \le t \le 10^4). The description of the test cases follows.

The first line of each test case contains two integers nn and kk (2n21052 \le n \le 2 \cdot 10^5; 1kn11 \le k \le n - 1) — length of the permutation, and a distance between elements that can be swapped.

The second line of each test case contains nn integers p1,p2,,pnp_1, p_2, \dots, p_n (1pin1 \le p_i \le n) — elements of the permutation pp.

It is guaranteed that the sum of nn over all test cases does not exceed 21052 \cdot 10 ^ 5.

Output

For each test case print

  • 0, if it is possible to sort the permutation without preliminary exchange;
  • 1, if it is possible to sort the permutation with one preliminary exchange, but not possible without preliminary exchange;
  • -1, if it is not possible to sort the permutation with at most one preliminary exchange.

Sample Input 1

6
4 1
3 1 2 4
4 2
3 4 1 2
4 2
3 1 4 2
10 3
4 5 9 1 8 6 10 2 3 7
10 3
4 6 9 1 8 5 10 2 3 7
10 3
4 6 9 1 8 5 10 3 2 7

Sample Output 1

0
0
1
0
1
-1

Note

In the first test case, there is no need in preliminary exchange, as it is possible to swap (p1,p2)(p_1, p_2) and then (p2,p3)(p_2, p_3).

In the second test case, there is no need in preliminary exchange, as it is possible to swap (p1,p3)(p_1, p_3) and then (p2,p4)(p_2, p_4).

In the third test case, you need to apply preliminary exchange to (p2,p3)(p_2, p_3). After that the permutation becomes [3,4,1,2][3, 4, 1, 2] and can be sorted with k=2k = 2.