#include <bits/stdc++.h>   using namespace std;   long long f[1001][1001], s[1001][1001];   long long a[10001], ans[10001];   int main() {     int n, m, k;     cin >> n >> k;     for (int i = 1; i <= n; i++) {       scanf( %lld , &a[i]);     }     sort(a + 1, a + n + 1);     a[0] = -10080124100;     long long sum = 0;     for (int t = 1; t * (k - 1) <= a[n]; t++) {       s[0][0] = f[0][0] = 1;       int l = 0;       for (int i = 1; i <= n; i++) {         while (a[l] <= a[i] - t) l++;         for (int j = 0; j <= k; j++) {           if (j != 0) f[i][j] = s[l - 1][j - 1] % 998244353;           s[i][j] = (s[i - 1][j] + f[i][j]) % 998244353;         }         sum = (sum + f[i][k]) % 998244353;       }     }     cout << sum << endl;     return 0;   }   