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], dp[1005][1005], qzh[1005][1005], ans, lst[1005];
int n, k;
inline int cal(int x) {
  for (int i = 1; i <= n; i++)
    while (a[i] - a[lst[i]] < x) --lst[i];
  dp[0][0] = qzh[0][0] = 1;
  for (int i = 1; i <= n; i++) {
    qzh[i][0] = 1;
    for (int j = 1; j <= k; j++)
      dp[i][j] = qzh[lst[i]][j - 1],
      qzh[i][j] = (qzh[i - 1][j] + dp[i][j]) % 998244353;
  }
  return qzh[n][k];
}
signed main(int argc, char** argv) {
  cin >> n >> k;
  for (int i = 1; i <= n; i++) cin >> a[i];
  sort(a + 1, a + n + 1), a[0] = -1e9;
  for (int i = 1; i <= n; i++) lst[i] = i;
  for (int i = 1; i <= 100000 / (k - 1) + 1; i++)
    ans = (cal(i) + ans) % 998244353;
  cout << ans;
  return 0;
}
