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 n, k, a[1000 + 5];
int ans, dp[1000 + 5][1000 + 5];
int sol(int x) {
  for (int i = 0; i <= n; i++)
    for (int j = 0; j <= k; j++) dp[i][j] = 0;
  dp[0][0] = 1;
  int pos = 0;
  for (int i = 1; i <= n; i++) {
    while (a[i] - a[pos + 1] >= x) pos++;
    for (int j = 0; j <= k; j++) dp[i][j] += dp[i - 1][j];
    for (int j = 1; j <= k; j++)
      dp[i][j] = (dp[i][j] + dp[pos][j - 1]) % 998244353;
  }
  return dp[n][k];
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  sort(a + 1, a + n + 1);
  for (int i = 1; i <= 100000 / (k - 1); i++) ans = (ans + sol(i)) % 998244353;
  printf("%d", ans);
}
