Sequence and Swaps

1000ms

524288K

Description:

You are given a sequence $$$a$$$ consisting of $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$, and an integer $$$x$$$. Your task is to make the sequence $$$a$$$ sorted (it is considered sorted if the condition $$$a_1 \le a_2 \le a_3 \le \dots \le a_n$$$ holds).

To make the sequence sorted, you may perform the following operation any number of times you want (possibly zero): choose an integer $$$i$$$ such that $$$1 \le i \le n$$$ and $$$a_i > x$$$, and swap the values of $$$a_i$$$ and $$$x$$$.

For example, if $$$a = [0, 2, 3, 5, 4]$$$, $$$x = 1$$$, the following sequence of operations is possible:

choose $$$i = 2$$$ (it is possible since $$$a_2 > x$$$), then $$$a = [0, 1, 3, 5, 4]$$$, $$$x = 2$$$;
choose $$$i = 3$$$ (it is possible since $$$a_3 > x$$$), then $$$a = [0, 1, 2, 5, 4]$$$, $$$x = 3$$$;
choose $$$i = 4$$$ (it is possible since $$$a_4 > x$$$), then $$$a = [0, 1, 2, 3, 4]$$$, $$$x = 5$$$.

Calculate the minimum number of operations you have to perform so that $$$a$$$ becomes sorted, or report that it is impossible.

Input:

The first line contains one integer $$$t$$$ ($$$1 \le t \le 500$$$) — the number of test cases.

Each test case consists of two lines. The first line contains two integers $$$n$$$ and $$$x$$$ ($$$1 \le n \le 500$$$, $$$0 \le x \le 500$$$) — the number of elements in the sequence and the initial value of $$$x$$$.

The second line contains $$$n$$$ integers $$$a_1$$$, $$$a_2$$$, ..., $$$a_n$$$ ($$$0 \le a_i \le 500$$$).

The sum of values of $$$n$$$ over all test cases in the input does not exceed $$$500$$$.

Output:

For each test case, print one integer — the minimum number of operations you have to perform to make $$$a$$$ sorted, or $$$-1$$$, if it is impossible.

Sample Input:

6
4 1
2 3 5 4
5 6
1 1 3 4 4
1 10
2
2 10
11 9
2 10
12 11
5 18
81 324 218 413 324

Sample Output:

Informação

Provedor Codeforces

Código CF1455D