#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;

const int mx = 200100;
mint fact[mx], ifact[mx];

void table_build(){
    fact[0] = 1;
    for (int i = 1; i < mx; i++){
        fact[i] = fact[i-1] * i;
    }
    ifact[mx-1] = fact[mx-1].inv();
    for (int i = mx-2; i >= 0; i--){
        ifact[i] = ifact[i+1] * (i+1);
    }
}

mint binom(int n, int r){
    if (n < 0 || n < r || r < 0) return 0;
    return fact[n] * ifact[r] * ifact[n-r];
}
mint inv(int n){
    if (n <= 0) return 0;
    return ifact[n] * fact[n-1];
}

auto get0(int m, int r){
    if (m < 0 || r < 0) return mint(0);
    return binom(m+r+1,r+1);
};
auto get1(int m, int r){
    if (m < 0 || r < 0) return mint(0);
    return binom(r+m+1,r) * m * (m+1) * inv(r+2);
};
auto get2(int m, int r){
    if (m < 0 || r < 0) return mint(0);
    return binom(r+m+1,r) * m * (m+1) * (ll(r+2)*m+1) * inv(r+2) * inv(r+3);
};

void input(int &x){
    static char c;
    x = 0;
    while ((c = getchar_unlocked() ^ 48) < 10){
        x *= 10;
        x += c;
    }
}

int main(){
    table_build();
    int n, k; input(n), input(k);
    vector<int> a(n);
    for (auto &x : a) input(x);
    sort(a.begin(),a.end());
    for (int i = n-2; i >= 0; i--){
        a[i+1] -= a[i];
    }
    mint ans = fact[n] * (n-1) * a[0];
    for (int i = 1; i < n; i++){
        mint md = get0(n-2*k-i,i-2) * (i-1) * (n-2*k-i+1) 
                + get1(n-2*k-i,i-2) * (-(i-1) + n-2*k-i+1)
                + get2(n-2*k-i,i-2) * (-1);
        mint lr = get0(n-k-i-1,i-1) * (n-k-i)
                + get1(n-k-i-1,i-1) * (-1);
        mint sum = md + lr*2;
        ans += sum * fact[i] * fact[n-i] * a[i];
    }
    cout << ans.val() << '\n';
}