#include <bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
using mint=modint998244353;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)


int main() {
    int N, K;
    cin >> N >> K;
    vector<int> A(N + 1), D(N);
    rep(i, 0, N) cin >> A[i];
    sort(A.begin(), A.end());
    rep(i, 0, N) D[i] = A[i + 1] - A[i];
    
    vector<mint> fact(N + 1, 1), fact_inv(N + 1, 1);
    rep(i, 0, N) fact[i + 1] = fact[i] * (i + 1);
    fact_inv[N] = fact[N].inv();
    for(int i = N; i > 0; i--) fact_inv[i - 1] = fact_inv[i] * i;
    
    vector<mint> g(N);
    rep(i, 0, N) g[i] = D[i] * fact[N - i];
    auto tmp = convolution(g, fact_inv);
    
    mint ans = 0;
    rep(i, 1, N){
    	int X = N - min(K, i) - min(K, N - i);
    	ans += tmp[X] * fact[X];
    }
    cout << ans.val() << "\n";
}