#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,a,b) for(int i=int(a);i<int(b);i++)
struct mint{
    static constexpr int  m = 998244353;
    int x;
    mint() : x(0){}
    mint(ll x_):x(x_%m){if(x<0)x+=m;}
    mint &operator+=(mint b){if((x+=b.x)>=m)x-=m; return *this;}
    mint &operator-=(mint b){if((x-=b.x)<0)x+=m; return *this;}
    mint &operator*=(mint b){x=ll(x)*b.x%m; return *this;}
    mint pow(ll e) const {
        mint r = 1,b =*this;
        while(e){
            if(e&1) r*=b;
            b*=b;
            e>>=1;
        }
        return r;
    }
    mint inv(){return pow(m-2);}
    mint &operator/=(mint b){return *this*=b.pow(m-2);}
    friend mint operator+(mint a,mint b){return a+=b;}
    friend mint operator-(mint a,mint b){return a-=b;}
    friend mint operator/(mint a,mint b){return a/=b;}
    friend mint operator*(mint a,mint b){return a*=b;}
};


int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N,K;
	cin>>N>>K;
	vector<ll> A(N);
	rep(i,0,N) cin>>A[i];
	assert(N<=7000);
	sort(A.begin(),A.end());
	auto D=A;
	for(int i=N-1;i>0;i--) D[i]-=D[i-1];
	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;
	auto P=[&](ll a,ll b) -> mint {
		if(a<b||a<0) return 0;
		return fact[a]*fact_inv[a-b];
	};
	mint ans=0;
	rep(i,0,N-1){
		int a=N-min(K,i+1)-min(K,N-i-1);
		rep(j,0,N){
			ans+=P(a,j)*fact[N-j]*mint(D[j]);
		}
	}
	cout<<ans.x<<"\n";
}