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 P = 998244353;
const int maxn = 1003;
const int INF = 1e9;
int a[maxn], s[maxn][maxn];
int add(int x, int y) {
  x += y;
  return x >= P ? x - P : x;
}
int read() {
  int c = 0;
  char ch = getchar();
  while (ch < '0' || '9' < ch) ch = getchar();
  while ('0' <= ch && ch <= '9') c = c * 10 + ch - '0', ch = getchar();
  return c;
}
int main() {
  int n = read(), k = read();
  for (int i = 1; i <= n; ++i) a[i] = read();
  sort(a + 1, a + 1 + n);
  a[0] = -INF;
  int ans = 0;
  for (int d = 1; d <= a[n] / (k - 1); ++d) {
    for (int i = 0; i <= n; ++i) s[0][i] = 1;
    for (int j = 1; j <= k; ++j) {
      for (int i = 1, l = 0; i <= n; ++i) {
        while (a[i] - a[l] >= d) ++l;
        s[j][i] = add(s[j][i - 1], s[j - 1][l - 1]);
      }
    }
    ans = add(ans, s[k][n]);
  }
  cout << ans % P << endl;
}
