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.io.*;
import java.util.*;
 
public class CF1188C extends PrintWriter {
	CF1188C() { super(System.out, true); }
	Scanner sc = new Scanner(System.in);
	public static void main(String[] $) {
		CF1188C o = new CF1188C(); o.main(); o.flush();
	}
 
	static final int MD = 998244353;
	void main() {
		int n = sc.nextInt();
		int k = sc.nextInt();
		int[] aa = new int[n];
		for (int i = 0; i < n; i++)
			aa[i] = sc.nextInt();
		Arrays.sort(aa);
		int[] dp = new int[n];
		int ans = 0;
		for (int x = 1; x * (k - 1) <= aa[n - 1] - aa[0]; x++) {
			Arrays.fill(dp, 1);
			for (int h = 1; h < k; h++) {
				for (int i = 1; i < n; i++)
					dp[i] = (dp[i] + dp[i - 1]) % MD;
				for (int j = n - 1, i = j; j >= 0; j--) {
					while (i >= 0 && aa[j] - aa[i] < x)
						i--;
					dp[j] = i >= 0 ? dp[i] : 0;
				}
			}
			for (int i = 0; i < n; i++)
				ans = (ans + dp[i]) % MD;
		}
		println(ans);
	}
}