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 Codeforces {
    static FastReader sc=new FastReader();
	static PrintWriter out=new PrintWriter(System.out);
	static long mod=1000000007;
	static long mod1=998244353;
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		int t=I();
		while(t-->0)
		{
			int n=I();
			int k=I();
			int a[]=new int[n];
			HashSet<Integer> hs=new HashSet<>();
			for(int i=0;i<n;i++){
				a[i]=I();
				hs.add(a[i]);
			}
			if(k==1){
				if(hs.size()!=1)out.println("-1");
				else out.println("1");
			}else{
				// if(k==hs.size())out.println("1");
				// else
				// out.println((hs.size()/k)+1);
				// out.println((hs.size()+(hs.size()-2))/k);
				out.println((((hs.size()-k<0?0:hs.size()-k)+(k-1)-1)/(k-1))+1);
			}
		}
		out.close();
	}
	public static class pair
    {
    	long a;
    	long b;
    	public pair(long val,long index)
    	{
    	    a=val;
    	    b=index;
    	}
    }
	public static class myComp implements Comparator<pair>
	{
		//sort in ascending order.
		// public int compare(pair p1,pair p2)
		// {
		// 	if(p1.a==p2.a)
    	//     return 0;
    	//     else if(p1.a<p2.a)
    	//     return 1;
    	//     else
    	//     return -1;
		// }
		//sort in descending order.
		public int compare(pair p1,pair p2)
    	{
    	    if(p1.a==p2.a)
    	    return 0;
    	    else if(p1.a<p2.a)
    	    return 1;
    	    else
    	    return -1;
    	}
	}
	public static long fact(long n)
	{
		long fact=1;
		for(long i=2;i<=n;i++){
			fact=((fact%mod)*(i%mod))%mod;
		}
		return fact;
	}
	public static long fact(int n)
	{
		long fact=1;
		for(int i=2;i<=n;i++){
			fact=((fact%mod)*(i%mod))%mod;
		}
		return fact;
	} 
	public static long kadane(long a[],int n)
	{
		long max_sum=Long.MIN_VALUE,max_end=0;
		for(int i=0;i<n;i++){
			max_end+=a[i];
			if(max_sum<max_end){max_sum=max_end;}
			if(max_end<0){max_end=0;}
		}
		return max_sum;
	}
	public static void DFS(ArrayList<Integer> arr[],int s,boolean visited[])
	{
		visited[s]=true;
		for(int i:arr[s]){
			if(!visited[i]){
				DFS(arr,i,visited);
			}
		}
	}
	public static int BS(long a[],long x,int ii,int jj)
	{
		// int n=a.length;
		int mid=0;
		int i=ii,j=jj;
		while(i<j)
		{
			mid=(i+j)/2;
			if(a[mid]>x)
			j=mid-1;
			else if(a[mid]<x)
			i=mid+1;
			else return mid;
		}
		if(a[i]>x)
		return i-1;
		return i;
	}
	public static ArrayList<Integer> primeSieve(int n)
	{
	    ArrayList<Integer> arr=new ArrayList<>();
	    boolean prime[] = new boolean[n + 1];
        for (int i = 0; i <= n; i++)
        prime[i] = true;
        for (int p = 2; p * p <= n; p++)
        {
            if (prime[p] == true)
            {
                for (int i = p * p; i <= n; i += p)
                prime[i] = false;
            }
        }
        for (int i = 2; i <= n; i++)
        {
            if (prime[i] == true)
            arr.add(i);
        }
        return arr;
	}

	// Fenwick / BinaryIndexed  Tree  USE IT - FenwickTree ft1=new FenwickTree(n);
	public static class FenwickTree
	{
		long farr[];
		int n;
		public FenwickTree(int c)
		{
			n=c+1;
			farr=new long[n];
		}
		public void update_range(int l,int r,long p)
		{
			update(l,p);
			update(r+1,(-1)*p);
		}
		public void update(int x,long p)
		{
			for(;x<n;x+=x&(-x))
			{
				farr[x]+=p;
			}
		}
		public long get(int x)
		{
			long ans=0;
			for(;x>0;x-=x&(-x))
			{
				ans=ans+farr[x];
			}
			return ans;
		}
	}

	//Disjoint Set Union
	public static class DSU
	{
	    static int par[],rank[];
	    public DSU(int c)
	    {
	        par=new int[c+1];
	        rank=new int[c+1];
	        for(int i=0;i<=c;i++)
	        {
	            par[i]=i;
	            rank[i]=0;
	        }
	    }
	    public static int find(int a)
	    {
	        if(a==par[a])
	        return a;
	        return par[a]=find(par[a]);
	    }
	    public static void union(int a,int b)
	    {
	        int a_rep=find(a),b_rep=find(b);
	        if(a_rep==b_rep)
	        return;
	        if(rank[a_rep]<rank[b_rep])
	        par[a_rep]=b_rep;
	        else if(rank[a_rep]>rank[b_rep])
	        par[b_rep]=a_rep;
	        else
	        {
	            par[b_rep]=a_rep;
	            rank[a_rep]++;
	        }
	    }
	}

	//SEGMENT TREE CODE

	// public static void segmentUpdate(int si,int ss,int se,int qs,int qe,long x)
	// {
	// 	if(ss>qe || se<qs)return;
	// 	if(qs<=ss && qe>=se)
	// 	{
	// 		seg[si][0]+=1L;
	// 		seg[si][1]+=x*x;
	// 		seg[si][2]+=2*x;
	// 		return;
	// 	}
	// 	int mid=(ss+se)/2;
	// 	segmentUpdate(2*si+1,ss,mid,qs,qe,x);
	// 	segmentUpdate(2*si+2,mid+1,se,qs,qe,x);
	// }
	// public static long segmentGet(int si,int ss,int se,int x,long f,long s,long t,long a[])
	// {
	// 	if(ss==se && ss==x)
	// 	{
	// 		f+=seg[si][0];
	// 		s+=seg[si][1];
	// 		t+=seg[si][2];
	// 		long ans=a[x]+(f*((long)x+1L)*((long)x+1L))+s+(t*((long)x+1L));
	// 		return ans;
	// 	}
	// 	int mid=(ss+se)/2;
	// 	if(x>mid){
	// 		return segmentGet(2*si+2,mid+1,se,x,f+seg[si][0],s+seg[si][1],t+seg[si][2],a);
	// 	}else{
	// 		return segmentGet(2*si+1,ss,mid,x,f+seg[si][0],s+seg[si][1],t+seg[si][2],a);
	// 	}
	// }

	
    public static class myComp1 implements Comparator<pair1>
    {
		//sort in ascending order.
    	public int compare(pair1 p1,pair1 p2)
    	{
    	    if(p1.a==p2.a)
    	    return 0;
    	    else if(p1.a<p2.a)
    	    return -1;
    	    else
    	    return 1;
    	}
		//sort in descending order.
		// public int compare(pair p1,pair p2)
    	// {
    	//     if(p1.a==p2.a)
    	//     return 0;
    	//     else if(p1.a<p2.a)
    	//     return 1;
    	//     else
    	//     return -1;
    	// }
    }
	public static class pair1
    {
    	long a;
    	long b;
    	public pair1(long val,long index)
    	{
    	    a=val;
    	    b=index;
    	}
    }
    public static ArrayList<pair1> mergeIntervals(ArrayList<pair1> arr)
	{
	    //****************use this in main function-Collections.sort(arr,new myComp1());
	    ArrayList<pair1> a1=new ArrayList<>();
	    if(arr.size()<=1)
	    return arr;
	    a1.add(arr.get(0));
	    int i=1,j=0;
	    while(i<arr.size())
	    {
	        if(a1.get(j).b<arr.get(i).a)
	        {
	           a1.add(arr.get(i));
	           i++;
	           j++;
	        }
	        else if(a1.get(j).b>arr.get(i).a && a1.get(j).b>=arr.get(i).b)
	        {
	            i++;
	        }
	        else if(a1.get(j).b>=arr.get(i).a)
	        {
	            long a=a1.get(j).a;
	            long b=arr.get(i).b;
	            a1.remove(j);
	            a1.add(new pair1(a,b));
	            i++;
	        }
	    }
	    return a1;
	}
	public static boolean palindrome(String s,int n)
	{
		for(int i=0;i<=n/2;i++){
			if(s.charAt(i)!=s.charAt(n-i-1)){
				return false;
			}
		}
		return true;
	}
	public static long countDigit(long n)
	{
	    long sum=0;
	    while(n!=0)
	    {
	        sum++;
	        n=n/10;
	    }
	    return sum;
	}
	public static long digitSum(long n)
	{
	    long sum=0;
	    while(n!=0)
	    {
	        sum=sum+n%10;
	        n=n/10;
	    }
	    return sum;
	}
	public static long gcd(long a,long b)
	{
	    if(b==0)
	    return a;
	    else
	    return gcd(b,a%b);
	}
	public static boolean prime(int n) 
	{ 
	    if (n <= 1) 
	        return false; 
	    if (n <= 3) 
	        return true; 
	    if (n % 2 == 0 || n % 3 == 0) 
	        return false; 
	    double sq=Math.sqrt(n);
	  
	    for (int i = 5; i <= sq; i = i + 6) 
	        if (n % i == 0 || n % (i + 2) == 0) 
	            return false; 
	    return true; 
	} 
    public static boolean prime(long n) 
	{ 
	    if (n <= 1) 
	        return false; 
	    if (n <= 3) 
	        return true; 
	    if (n % 2 == 0 || n % 3 == 0) 
	        return false; 
	    double sq=Math.sqrt(n);
	
	    for (int i = 5; i <= sq; i = i + 6) 
	        if (n % i == 0 || n % (i + 2) == 0) 
	            return false; 
	    return true; 
	} 
	public static int gcd(int a,int b)
	{
	    if(b==0)
	    return a;
	    else
	    return gcd(b,a%b);
	}
	public static void printArray(long a[])
	{
		for(int i=0;i<a.length;i++){
			out.print(a[i]+" ");
		}
		out.println();
	}
	public static void printArray(ArrayList<Integer> arr)
	{
		for(int i=0;i<arr.size();i++){
			out.print(arr.get(i)+" ");
		}
		out.println();
	}
	public static long pwr(long m,long n)
	{
		long res=1;
		m=m%mod;
		if(m==0)
		return 0;
		while(n>0)
		{
			if((n&1)!=0)
			{
				res=(res*m)%mod;
			}
			n=n>>1;
			m=(m*m)%mod;
		}
		return res;
	}
	public static void sort(int[] A)
	{
        int n = A.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i)
		{
            int tmp = A[i];
            int randomPos = i + rnd.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
        Arrays.sort(A);
    }
    public static void sort(long[] A)
	{
	    int n = A.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i)
		{
            long tmp = A[i];
            int randomPos = i + rnd.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
	    Arrays.sort(A);
	}
	public static int I(){return sc.I();}
    public static long L(){return sc.L();}
    public static String S(){return sc.S();}
    public static double D(){return sc.D();}
}
class FastReader {  
    BufferedReader br;
    StringTokenizer st;
    public FastReader(){
        br = new BufferedReader(new InputStreamReader(System.in));
    }
    String next(){
        while (st == null || !st.hasMoreElements()){
            try {
                st = new StringTokenizer(br.readLine());
            }
            catch (IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }
    int I(){ 
        return Integer.parseInt(next());
    }
    long L(){ 
        return Long.parseLong(next());
    }
    double D(){
         return Double.parseDouble(next());
    }
    String S(){
        String str = "";
        try 
        {
            str = br.readLine();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        return str;
    }
}
