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.util.*;
    import java.lang.*;
    import java.io.*;   
    import java.math.*;
    public class Prac{     
        static class InputReader { 
            private final InputStream stream;
            private final byte[] buf = new byte[8192];
            private int curChar, snumChars;
            public InputReader(InputStream st) {
                this.stream = st;
            } 
            public int read() {
                if (snumChars == -1)
                    throw new InputMismatchException();
                if (curChar >= snumChars) {
                    curChar = 0;
                    try {
                        snumChars = stream.read(buf);
                    } 
                    catch (IOException e) {
                        throw new InputMismatchException();
                    }
                    if (snumChars <= 0)
                        return -1;
                }
                return buf[curChar++];
            }
            public int ni() {
                int c = read();
                while (isSpaceChar(c)) {
                    c = read();
                }
                int sgn = 1;
                if (c == '-') {
                    sgn = -1;
                    c = read();
                }
                int res = 0;
                do {
                    res *= 10;
                    res += c - '0';
                    c = read();
                } while (!isSpaceChar(c));
                return res * sgn;
            } 
            public long nl() {
                int c = read();
                while (isSpaceChar(c)) {
                c = read();
                }
                int sgn = 1;
                if (c == '-') {
                    sgn = -1;
                    c = read();
                }
                long res = 0;
                do {
                    res *= 10;
                    res += c - '0';
                    c = read();
                } while (!isSpaceChar(c));
                return res * sgn;
            } 
            public int[] nia(int n) {
                int a[] = new int[n];
                for (int i = 0; i < n; i++) {
                    a[i] = ni();
                }
                return a;
            } 
            public int[] nia1(int n) {
                int a[] = new int[n+1];
                for (int i = 1; i <=n; i++) {
                    a[i] = ni();
                }
                return a;
            } 
            public long[] nla(int n) {
                long a[] = new long[n];
                for (int i = 0; i < n; i++) {
                    a[i] = nl();
                }
                return a;
            } 
            public long[] nla1(int n) {
                long a[] = new long[n+1];
                for (int i = 1; i <= n; i++) {
                    a[i] = nl();
                }
                return a;
            } 
            public Long[] nLa(int n) {
                Long a[] = new Long[n];
                for (int i = 0; i < n; i++) {
                    a[i] = nl();
                }
                return a;
            } 
            public Long[] nLa1(int n) {
                Long a[] = new Long[n+1];
                for (int i = 1; i <= n; i++) {
                    a[i] = nl();
                }
                return a;
            } 
            public Integer[] nIa(int n) {
                Integer a[] = new Integer[n];
                for (int i = 0; i < n; i++) {
                    a[i] = ni();
                }
                return a;
            } 
            public Integer[] nIa1(int n) {
                Integer a[] = new Integer[n+1];
                for (int i = 1; i <= n; i++) {
                    a[i] = ni();
                }
                return a;
            } 
            public String rs() {
                int c = read();
                while (isSpaceChar(c)) {
                    c = read();
                }
                StringBuilder res = new StringBuilder();
                do {
                    res.appendCodePoint(c);
                        c = read();
                } while (!isSpaceChar(c));
                return res.toString();
            }
            public String nextLine() {
                int c = read();
                while (isSpaceChar(c))
                    c = read();
                StringBuilder res = new StringBuilder();
                do {
                    res.appendCodePoint(c);
                    c = read();
                } while (!isEndOfLine(c));
                return res.toString();
            } 
            public boolean isSpaceChar(int c) {
                return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
            }

            private boolean isEndOfLine(int c) {
                return c == '\n' || c == '\r' || c == -1;
            } 
        }
        public static class Key {
            private final int x, y;
            public Key(int x, int y) {
                this.x = x; this.y = y;
            }
            @Override
            public boolean equals(Object o) {
                if (this == o) return true;
                if (!(o instanceof Key)) return false;
                Key key = (Key) o;
                return x == key.x && y == key.y;
            }   
            @Override
            public int hashCode() {
                int result = x;
                result = 31 * result + y;
                return result;
            }
        }
        static class Pair{
                int x,y;
                Pair(int a,int b){
                        x=a;y=b;
                }
    //            @Override
    //            public int compareTo(Pair p) {
    //                    if(x==p.x) return y-p.y;
    //                    return x-p.x;
    //            }
        }
        static void shuffleArray(int temp[]){
            int n = temp.length;
            Random rnd = new Random();
            for(int i=0; i<n; ++i){
                int tmp = temp[i];
                int randomPos = i + rnd.nextInt(n-i);
                temp[i] = temp[randomPos];
                temp[randomPos] = tmp;
            }   
        }
        static long gcd(long a,long b){ return b==0?a:gcd(b,a%b);}
        static long lcm(long a,long b){return (a/gcd(a,b))*b;}
        static PrintWriter w = new PrintWriter(System.out);
        static long mod=998244353L,mod1=1000000007;
        //static int r[]={0,1,0,-1}, c[]={1,0,-1,0};
        static long modInverse(long a, long m){
            long num=m;
            long x=1;
            long power=a%mod;
            while(num>0){
                  if(num%2==1){
                      x=(x*power)%mod;
                }
                num>>=1;
                power=(power*power)%mod;         
            }
            return x;
        }
        static long fact[]=new long[1000005];
        public static void findFact(){
            fact[0]=1;
            for(int i=1;i<=1000000;i++){
                fact[i]=(i*fact[i-1])%mod;
            }
        } 
        static long ncrWithMod(int n,int r){
            if(n<r)return 0L;

            return (fact[n]*modInverse((fact[r]*fact[n-r])%mod,mod-2))%mod;
        }
        
        public static void main(String [] args){
            InputReader sc=new InputReader(System.in); 
            int t = sc.ni();
            while(t -- > 0 ){
                int n = sc.ni();
                int k = sc.ni();
                int arr[] = sc.nia(n);
                int sum[] = new int[n];
                int ans = 0;
                Set<Integer> set = new HashSet<>();
                boolean f = false;
                for(int i = 0 ; i < n ; i ++){
                    set.add(arr[i]);
                    if(set.size() > k){
                        ans++;
                        set.clear();
                        set.add(arr[i]);
                        set.add(0);
                    }
                    if(set.size() > k){
                        f = true;
                    }
                }
                if(set.size() > 0)ans++;
                if(f)w.println(-1);
                else w.println(ans);
            }
            w.close();
        }
    }
    