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;
long long f[1011][1011], ans[100011], g[1011], a[1011], n = 0, s = 0,
                                                        allans = 0;
signed main() {
  register long long i = 0, j = 0, k = 0, p = 0;
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> s;
  for (i = 1; i <= n; ++i) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  a[0] = -0x3f3f3f3f;
  for (i = a[n] / (s - 1); i; --i) {
    for (j = 0; j <= n; ++j) {
      f[0][j] = 1;
    }
    for (j = 1; j <= s; ++j) {
      for (p = j - 1, k = j; k <= n; ++k) {
        for (; p <= k && a[k] - a[p] >= i; ++p)
          ;
        if (j >= 2) {
          f[j][k] =
              (f[j][k - 1] + f[j - 1][p - 1] + 998244353 - f[j - 1][j - 2]) %
              998244353;
        } else {
          f[j][k] = f[j][k - 1] + f[j - 1][p - 1];
        }
      }
    }
    allans = (allans + f[s][n]) % 998244353;
  }
  cout << allans << endl;
  return 0;
}
