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 = 1e9;
const long long inf64 = 1e18;
const int mod = 998244353;
inline int _sum(int a, int b) { return (a + b < mod ? a + b : a + b - mod); }
inline int _sub(int a, int b) { return (a >= b ? a - b : a - b + mod); }
inline int _mul(int a, int b) { return (1ll * a * b) % mod; }
inline void _inc(int& x, int y) {
  if ((x += y) >= mod) {
    x -= mod;
  }
}
inline void _dec(int& x, int y) {
  if ((x -= y) < 0) {
    x += mod;
  }
}
const int N = 1005;
const int X = 1e5 + 5;
int used[X];
int n, k;
int a[N];
int f[X], g[X];
int dp[N][N], sm[N][N];
int calc(int x) {
  for (int i = 0; i <= n; i++) {
    fill(dp[i], dp[i] + k + 1, 0);
    fill(sm[i], sm[i] + k + 1, 0);
  }
  dp[0][0] = 1;
  sm[0][0] = 1;
  for (int j = 0, i = 1; i <= n; i++) {
    while (j + 1 <= i && a[i] - a[j + 1] >= x) j++;
    for (int c = 0; c < k; c++) {
      _inc(dp[i][c + 1], sm[j][c]);
    }
    for (int c = 0; c <= k; c++) {
      sm[i][c] = _sum(sm[i - 1][c], dp[i][c]);
    }
  }
  int res = 0;
  for (int i = k; i <= n; i++) {
    _inc(res, dp[i][k]);
  }
  return res;
}
bool can(int x) {
  int cnt = 0;
  int i = 1;
  while (i <= n) {
    cnt++;
    int j = lower_bound(a + 1, a + n + 1, a[i] + x) - a;
    j = max(j, i + 1);
    i = j;
  }
  return cnt >= k;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  for (int j = 1; j <= n; j++) {
    for (int i = 1; i < j; i++) {
      used[a[j] - a[i]] = 1;
    }
  }
  int bx = 1;
  while (can(bx)) bx <<= 1;
  bx = min(bx, X - 1);
  for (int x = 0; x <= bx; x++) {
    if (!used[x]) continue;
    f[x] = calc(x);
  }
  for (int sum = 0, i = bx; i >= 0; i--) {
    if (!used[i]) continue;
    g[i] = _sub(f[i], sum);
    _inc(sum, g[i]);
  }
  int res = 0;
  for (int x = 0; x <= bx; x++) {
    _inc(res, _mul(x, g[x]));
  }
  cout << res << "\n";
  return 0;
}
