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 maxn = 1e3 + 2;
const int mod = 998244353;
int n, k, ans;
int a[maxn];
int dp[maxn][maxn];
void DP() {
  for (int i = 1; i <= a[n] / (k - 1) + 1; i++) {
    dp[0][0] = 1;
    for (int l = 1, r = 0; l <= n; l++) {
      while (a[r + 1] + i <= a[l]) r++;
      dp[l][0] = dp[l - 1][0];
      for (int pos = 1; pos <= l && pos <= k; pos++)
        dp[l][pos] = (dp[l - 1][pos] + dp[r][pos - 1]) % mod;
    }
    ans = (ans + dp[n][k]) % mod;
  }
}
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  sort(a + 1, a + n + 1);
  DP();
  printf("%d", ans);
  return 0;
}
