#include <bits/stdc++.h>
using namespace std;
int inline read() {
  int num = 0, neg = 1;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') neg = -1;
    c = getchar();
  }
  while (isdigit(c)) {
    num = (num << 3) + (num << 1) + c - '0';
    c = getchar();
  }
  return num * neg;
}
const int maxn = 1010, mod = 998244353;
int n, k, a[maxn], f[maxn][maxn], s[maxn][maxn], ANS;
int main() {
  n = read();
  k = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  sort(a + 1, a + n + 1);
  a[0] = -2147483647;
  for (int ans = 1; ans <= a[n] / (k - 1); ans++) {
    f[0][0] = 1;
    s[0][0] = 1;
    int pl = 0, S = 0;
    for (int i = 1; i <= n; i++) {
      while (a[pl] <= a[i] - ans) pl++;
      for (int j = 0; j <= k; j++) {
        if (j) f[i][j] = s[pl - 1][j - 1];
        s[i][j] = (s[i - 1][j] + f[i][j]) % mod;
      }
      S = (S + f[i][k]) % mod;
    }
    ANS = (ANS + S) % mod;
  }
  cout << ANS;
  return 0;
}

### Prompt

Please formulate a Cpp solution to the following problem:

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.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int inline read() {
  int num = 0, neg = 1;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') neg = -1;
    c = getchar();
  }
  while (isdigit(c)) {
    num = (num << 3) + (num << 1) + c - '0';
    c = getchar();
  }
  return num * neg;
}
const int maxn = 1010, mod = 998244353;
int n, k, a[maxn], f[maxn][maxn], s[maxn][maxn], ANS;
int main() {
  n = read();
  k = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  sort(a + 1, a + n + 1);
  a[0] = -2147483647;
  for (int ans = 1; ans <= a[n] / (k - 1); ans++) {
    f[0][0] = 1;
    s[0][0] = 1;
    int pl = 0, S = 0;
    for (int i = 1; i <= n; i++) {
      while (a[pl] <= a[i] - ans) pl++;
      for (int j = 0; j <= k; j++) {
        if (j) f[i][j] = s[pl - 1][j - 1];
        s[i][j] = (s[i - 1][j] + f[i][j]) % mod;
      }
      S = (S + f[i][k]) % mod;
    }
    ANS = (ANS + S) % mod;
  }
  cout << ANS;
  return 0;
}

```