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 INF = 1 << 30;
const int MAXN = 1e3 + 5;
int arr[MAXN];
int dp[MAXN][MAXN], pref[MAXN][MAXN];
int le[MAXN];
const int MOD = 998244353;
int n, k;
int add(int a, int b) {
  a += b;
  while (a < 0) a += MOD;
  return a % MOD;
}
int mul(int a, int b) { return (long long)a * b % MOD; }
int solve(int x) {
  for (int i = 0; i <= k; i++) {
    for (int j = 0; j <= n; j++) {
      dp[i][j] = 0;
    }
  }
  le[0] = 0;
  for (int i = 1; i <= n; i++) {
    le[i] = le[i - 1];
    while (arr[i] - arr[le[i] + 1] >= x) le[i]++;
  }
  dp[0][0] = 1;
  for (int i = 0; i + 1 <= k; i++) {
    pref[i][0] = dp[i][0];
    for (int j = 1; j <= n; j++) {
      pref[i][j] = add(pref[i][j - 1], dp[i][j]);
    }
    for (int j = 1; j <= n; j++) {
      dp[i + 1][j] = pref[i][le[j]];
    }
  }
  int res = 0;
  for (int i = 1; i <= n; i++) res = add(res, dp[k][i]);
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> k;
  for (int i = 1; i <= n; ++i) {
    cin >> arr[i];
  }
  sort(arr + 1, arr + n + 1);
  int ans = 0;
  for (int i = 1; i <= arr[n] / (k - 1); ++i) {
    ans = add(ans, solve(i));
  }
  cout << ans << '\n';
  return 0;
}
