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;
const int mod = 998244353;
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a.begin(), a.end());
  int ans = 0;
  for (int x = 1; x <= a[n] / (k - 1); x++) {
    vector<vector<int>> presum(k + 1, vector<int>(n + 1));
    for (int i = 0; i <= n; i++) {
      presum[0][i] = 1;
    }
    for (int j = 1; j <= k; j++) {
      int p = 0;
      for (int i = j; i <= n; i++) {
        while (a[p + 1] + x <= a[i]) {
          p++;
        }
        (presum[j][i] += presum[j - 1][p] + presum[j][i - 1]) %= mod;
      }
    }
    (ans += presum[k][n]) %= mod;
  }
  cout << ans << endl;
  return 0;
}
