You are given a non-decreasing array of non-negative integers a_1, a_2, …, a_n. Also you are given a positive integer k.

You want to find m non-decreasing arrays of non-negative integers b_1, b_2, …, b_m, such that:

  * The size of b_i is equal to n for all 1 ≤ i ≤ m. 
  * For all 1 ≤ j ≤ n, a_j = b_{1, j} + b_{2, j} + … + b_{m, j}. In the other word, array a is the sum of arrays b_i. 
  * The number of different elements in the array b_i is at most k for all 1 ≤ i ≤ m. 



Find the minimum possible value of m, or report that there is no possible m.

Input

The first line contains one integer t (1 ≤ t ≤ 100): the number of test cases.

The first line of each test case contains two integers n, k (1 ≤ n ≤ 100, 1 ≤ k ≤ n).

The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_1 ≤ a_2 ≤ … ≤ a_n ≤ 100, a_n > 0).

Output

For each test case print a single integer: the minimum possible value of m. If there is no such m, print -1.

Example

Input


6
4 1
0 0 0 1
3 1
3 3 3
11 3
0 1 2 2 3 3 3 4 4 4 4
5 3
1 2 3 4 5
9 4
2 2 3 5 7 11 13 13 17
10 7
0 1 1 2 3 3 4 5 5 6


Output


-1
1
2
2
2
1

Note

In the first test case, there is no possible m, because all elements of all arrays should be equal to 0. But in this case, it is impossible to get a_4 = 1 as the sum of zeros.

In the second test case, we can take b_1 = [3, 3, 3]. 1 is the smallest possible value of m.

In the third test case, we can take b_1 = [0, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2] and b_2 = [0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2]. It's easy to see, that a_i = b_{1, i} + b_{2, i} for all i and the number of different elements in b_1 and in b_2 is equal to 3 (so it is at most 3). It can be proven that 2 is the smallest possible value of m.
import java.io.*;
import java.util.*;
import java.util.stream.Collectors;


/**
 * ti*zi+yi
 */
public class Main {

    void solve() {
        int n = in.nextInt();
        int k = in.nextInt();
        int[] a = in.nextInts(n);
        int count = (int) Arrays.stream(a).distinct().count();
        if (Arrays.stream(a).anyMatch(value -> value == 0)) {
            if (count == 1){
                out.println(0);
                return;
            }
            if (k==1){
                out.println(-1);
                return;
            }
            if (count<=k){
                out.println(1);
                return;
            }
            out.println((count-1+(k-2))/(k-1));
        }else{
            if (count == 1){
                out.println(1);
                return;
            }
            if (k==1){
                out.println(-1);
                return;
            }
            if (count<=k){
                out.println(1);
                return;
            }
            out.println((count-1+(k-2))/(k-1));
        }
    }

    static final boolean MULTI_TEST = true;

    // --------------------------------------------------------------------------------------------------------------
    // --------------------------------------------------HELPER------------------------------------------------------
    // --------------------------------------------------------------------------------------------------------------


    void run() {
        if (MULTI_TEST) {
            int t = in.nextInt();
            for (int i = 0; i < t; i++) {
                solve();
            }
        } else {
            solve();
        }
    }

    // --------------------ALGORITHM-------------------------

    static int MOD = 1000000007;

    public void sort(int[] arr) {
        List<Integer> tmp = Arrays.stream(arr).boxed().sorted().collect(Collectors.toList());
        for (int i = 0; i < arr.length; i++) {
            arr[i] = tmp.get(i);
        }
    }

    public void sortRev(int[] arr) {
        List<Integer> tmp = Arrays.stream(arr).boxed().sorted(Comparator.comparing((Integer x) -> x).reversed())
                .collect(Collectors.toList());
        for (int i = 0; i < arr.length; i++) {
            arr[i] = tmp.get(i);
        }
    }

    // --------------------SCANNER-------------------------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;

        public MyScanner(String fileName) {
            if (fileName != null) {
                try {
                    br = new BufferedReader(new FileReader(fileName));
                } catch (FileNotFoundException e) {
                    throw new RuntimeException(e);
                }
            } else {
                br = new BufferedReader(new InputStreamReader(System.in));
            }
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                st = new StringTokenizer(nextLine());
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] nextInts(int n) {
            int[] arr = new int[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextInt();
            }
            return arr;
        }

        boolean[] nextLineBools() {
            String line = nextLine();
            int n = line.length();
            boolean[] booleans = new boolean[n];
            for (int i = 0; i < n; i++) {
                booleans[i] = line.charAt(i) == '1';
            }
            return booleans;
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        public long[] nextLongs(int n) {
            long[] arr = new long[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextLong();
            }
            return arr;
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            try {
                String line = br.readLine();
                if (line == null) {
                    throw new RuntimeException("empty line");
                }
                return line;
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

    }

    // --------------------WRITER-------------------------
    public static class MyWriter extends PrintWriter {

        public static MyWriter of(String fileName) {
            if (fileName != null) {
                try {
                    return new MyWriter(new FileWriter(fileName));
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } else {
                return new MyWriter(new BufferedOutputStream(System.out));
            }
        }

        public MyWriter(FileWriter fileWriter) {
            super(fileWriter);
        }

        public MyWriter(OutputStream out) {
            super(out);
        }

        void println(int[] arr) {
            String line = Arrays.stream(arr).mapToObj(String::valueOf).collect(Collectors.joining(" "));
            println(line);
        }

    }

    // -----------------------BENCHMARK-------------------------
    public static class Benchmark {
        long time;

        public void reset() {
            time = System.currentTimeMillis();
        }

        public long calc() {
            long curTime = System.currentTimeMillis();
            long tmp = curTime - time;
            time = curTime;
            return tmp;
        }

    }


    // --------------------MAIN-------------------------

    public MyScanner in;
    public MyWriter out;
    public Benchmark bm;

    /**
     * run as `java Main`, `java Main input.txt' or `java Main input.txt output.txt'
     * add `-Xss256m` to increase stack size
     */
    public static void main(String[] args) {
        Main m = new Main();
        m.in = new MyScanner(args.length > 0 ? args[0] : null);
        m.out = MyWriter.of(args.length > 1 ? args[1] : null);
        m.bm = new Benchmark();
        m.run();
        m.out.close();
    }
}
