Yzk has an array consisting of integers . In one operation, he can select a continuous sub-array of exactly length , then change all elements in the sub-array to the minimum element in this sub-array.
Please help him found the minimum number of operations to make all elements in the array equal.

输入描述:

The first line contains one integer  --- the number of test cases.
The first line of each test case contains two integers  --- the length of array , and the length of sub-array Yzk should select.
The second line contains  integers . --- the elements of array .
It's guaranteed that the sum of  over all test cases doesn't exceed ().

输出描述:

For each test case, output an integer in one line --- the minimum number of operations to make all elements in the array  equal. If it's impossible to do it, output -1.

4
5 3
3 4 1000000 5 3
5 3
1 2 1 3 1
2 1
1 1
2 1
1 2

2
1
0
-1

In the first test case, we can do  operations as follows:
In the operation , select sub-array , the minimum element in  is , then array  changes to .
In the operation , select sub-array , the minimum element in  is , then array  changes to .