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;
mt19937 rng(static_cast<unsigned int>(
    chrono::steady_clock::now().time_since_epoch().count()));
template <typename num_t>
inline void add_mod(num_t& a, const int& b, const int& m) {
  a = (a + b) % m;
  if (a >= m) a -= m;
  if (a < 0) a += m;
}
template <typename num_t>
inline bool update_max(num_t& a, const num_t& b) {
  return a < b ? a = b, true : false;
}
template <typename num_t>
inline bool update_min(num_t& a, const num_t& b) {
  return a > b ? a = b, true : false;
}
template <typename num_t>
num_t gcd(num_t lhs, num_t rhs) {
  return !lhs ? rhs : gcd(rhs % lhs, lhs);
}
template <typename num_t>
num_t pw(num_t n, num_t k, const num_t& mod) {
  if (k == -1) k = mod - 2;
  num_t res = 1;
  for (; k > 0; k >>= 1) {
    if (k & 1) res = 1ll * res * n % mod;
    n = 1ll * n * n % mod;
  }
  return res % mod;
}
const int inf = 1e9 + 7;
const int mod = 998244353;
const long long ll_inf = 9ll * inf * inf + 7;
const int MAX_N = 1000 + 7;
int n, k;
vector<int> num;
long long dp[MAX_N][MAX_N];
int calc(int min_dist) {
  int last = 0;
  for (int i = 0; i < n; ++i) {
    while (last + 1 < i && num[i] - num[last + 1] >= min_dist) ++last;
    dp[i][1] = 1;
    if (i > last && num[i] - num[last] >= min_dist) {
      for (int j = 2; j <= k; ++j) {
        dp[i][j] = dp[last][j - 1];
      }
    } else {
      for (int j = 2; j <= k; ++j) dp[i][j] = 0;
    }
    if (i > 0) {
      for (int j = 1; j <= k; ++j) {
        dp[i][j] = (dp[i][j] + dp[i - 1][j]) % mod;
      }
    }
  }
  return dp[n - 1][k] % mod;
}
void solve() {
  cin >> n >> k;
  for (int i = (0), _b = (n); i < _b; ++i) {
    int u;
    cin >> u;
    num.push_back(u);
  }
  sort(num.begin(), num.end());
  const int MAX = 100000;
  vector<long long> f;
  for (int min_dist = 1; min_dist * (k - 1) <= MAX; ++min_dist) {
    f.push_back(calc(min_dist));
  }
  f.push_back(0);
  long long res = 0;
  for (int i = 0; i + 1 < f.size(); ++i) {
    add_mod(res, (i + 1) * (f[i] - f[i + 1]) % mod, mod);
  }
  cout << res << '\n';
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  const bool multiple_test = false;
  int test = 1;
  if (multiple_test) cin >> test;
  for (int i = 0; i < test; ++i) {
    solve();
  }
}
