#include <bits/stdc++.h>
using namespace std;
const int maxn = 1002;
inline long long read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + ch - '0';
    ch = getchar();
  }
  return f * x;
}
long long res = 0, n, k, a[maxn], f[maxn][maxn], s[maxn][maxn];
int main() {
  n = read();
  k = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  sort(a + 1, a + 1 + n);
  a[0] = -1e9;
  for (int p = 1; p * (k - 1) <= a[n]; p++) {
    int now = 0;
    f[0][0] = 1;
    s[0][0] = 1;
    for (int i = 1; i <= n; i++) {
      while (a[i] - a[now] >= p) now++;
      for (int j = 0; j <= k; j++) {
        if (j) f[i][j] = s[now - 1][j - 1] % 998244353;
        s[i][j] = (s[i - 1][j] + f[i][j]) % 998244353;
      }
      res = res + f[i][k];
    }
    res %= 998244353;
  }
  printf("%lld\n", res);
  return 0;
}

### Prompt

In Cpp, your task is to solve 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;
const int maxn = 1002;
inline long long read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + ch - '0';
    ch = getchar();
  }
  return f * x;
}
long long res = 0, n, k, a[maxn], f[maxn][maxn], s[maxn][maxn];
int main() {
  n = read();
  k = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  sort(a + 1, a + 1 + n);
  a[0] = -1e9;
  for (int p = 1; p * (k - 1) <= a[n]; p++) {
    int now = 0;
    f[0][0] = 1;
    s[0][0] = 1;
    for (int i = 1; i <= n; i++) {
      while (a[i] - a[now] >= p) now++;
      for (int j = 0; j <= k; j++) {
        if (j) f[i][j] = s[now - 1][j - 1] % 998244353;
        s[i][j] = (s[i - 1][j] + f[i][j]) % 998244353;
      }
      res = res + f[i][k];
    }
    res %= 998244353;
  }
  printf("%lld\n", res);
  return 0;
}

```