Let's call beauty of an array b_1, b_2, …, b_n (n > 1) — min_{1 ≤ i < j ≤ n} |b_i - b_j|.

You're given an array a_1, a_2, … a_n and a number k. Calculate the sum of beauty over all subsequences of the array of length exactly k. As this number can be very large, output it modulo 998244353.

A sequence a is a subsequence of an array b if a can be obtained from b by deletion of several (possibly, zero or all) elements.

Input

The first line contains integers n, k (2 ≤ k ≤ n ≤ 1000).

The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ 10^5).

Output

Output one integer — the sum of beauty over all subsequences of the array of length exactly k. As this number can be very large, output it modulo 998244353.

Examples

Input


4 3
1 7 3 5


Output


8

Input


5 5
1 10 100 1000 10000


Output


9

Note

In the first example, there are 4 subsequences of length 3 — [1, 7, 3], [1, 3, 5], [7, 3, 5], [1, 7, 5], each of which has beauty 2, so answer is 8.

In the second example, there is only one subsequence of length 5 — the whole array, which has the beauty equal to |10-1| = 9.
import java.util.*;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
 
public class ArrayBeauty
{
    public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(in, out);
        out.close();
    }
 
    static class Task
    {
        int N = 1005;
        int n,k,i,j;
        int mod = 998244353;
        int[] a = new int[N];
        int[][] f = new int[N][N];
        
        public void solve(InputReader in, PrintWriter out) 
        {
         
            int o,t,sol=0;
            
            n = in.nextInt();
            k = in.nextInt();
            
            for (i = 1; i <=n; ++i)
                a[i] = in.nextInt();
            Arrays.sort(a,1,n+1);
            for (o = 1; o * (k - 1) <= 100005; o++) 
            {
                f[0][0]=1;
                t=0;
                for(i=1;i<=n;i=i+1)
                {
                    while(a[t+1]+o<=a[i])
                        t++;
                    f[i][0]=f[i-1][0];
                    for(j=1;j<=i&&j<=k;j=j+1)
                        f[i][j]=(f[i-1][j]+f[t][j-1])%mod;
                }
                sol=(sol+f[n][k])%mod;
            }
            out.println(sol);
        }
    }

    static class InputReader 
    {
        public BufferedReader reader;
        public StringTokenizer tokenizer;
 
        public InputReader(InputStream stream) 
        {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }
 
        public String next() 
        {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
 
        public long nextLong() 
        {
            return Long.parseLong(next());
        }
        
        public int nextInt() 
        {
            return Integer.parseInt(next());
        }
    }
}