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;
inline int read() {
  int s = 0, w = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') w = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar();
  return s * w;
}
int a[1003];
long long x[1003][1003];
int main() {
  int n = read(), m = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  a[0] = -1919810;
  sort(a + 1, a + n + 1);
  int Max = a[n];
  long long ans = 0;
  for (int t = 1; t * (m - 1) <= a[n]; t++) {
    int tmp = 0;
    for (int i = 0; i <= n; i++) x[i][0] = 1;
    for (int i = 1; i <= n; i++) {
      while (a[tmp] <= a[i] - t) tmp++;
      for (int j = 1; j <= m; j++)
        x[i][j] = (x[i - 1][j] + x[tmp - 1][j - 1]) % 998244353LL;
    }
    ans += x[n][m], ans %= 998244353LL;
  }
  cout << ans << endl;
  return 0;
}
