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.
#include <bits/stdc++.h>
using namespace std;
int a[1005];
int dp[1005][1005], row_s[1005][1005];
int pre_index[1005];
int n, k;
int cal(int a, int b) { return (a + b) % 998244353; }
int this_beauty(int beauty) {
  pre_index[0] = 0;
  for (int i = 1; i <= n; i++) {
    pre_index[i] = pre_index[i - 1];
    while (a[i] - a[pre_index[i] + 1] >= beauty) pre_index[i]++;
  }
  row_s[1][0] = 0;
  for (int i = 1; i <= k; i++) {
    for (int j = i; j <= n; j++) {
      if (i == 1) {
        dp[i][j] = 1;
        row_s[i][j] = cal(row_s[i][j - 1], dp[i][j]);
        continue;
      }
      dp[i][j] = row_s[i - 1][pre_index[j]];
      row_s[i][j] = cal(row_s[i][j - 1], dp[i][j]);
    }
  }
  return row_s[k][n];
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  sort(a + 1, a + 1 + n);
  int max_beauty = (a[n] - a[1]) / (k - 1);
  int answer = 0;
  for (int i = 1; i <= max_beauty; i++) {
    answer = cal(answer, this_beauty(i));
  }
  printf("%d\n", answer);
  return 0;
}
