write a go solution for Description:
You are given a sequence a consisting of n integers a_1,a_2,...,a_n, and an integer x. Your task is to make the sequence a sorted (it is considered sorted if the condition a_1<=a_2<=a_3<=...<=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<=i<=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:

1. choose i=2 (it is possible since a_2>x), then a=[0,1,3,5,4], x=2;
2. choose i=3 (it is possible since a_3>x), then a=[0,1,2,5,4], x=3;
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 Format:
The first line contains one integer t (1<=t<=500) — the number of test cases.

Each test case consists of two lines. The first line contains two integers n and x (1<=n<=500, 0<=x<=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<=a_i<=500).

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

Output Format:
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.

Note:
None. Output only the code with no comments, explanation, or additional text.