#include <bits/stdc++.h>
using namespace std;
int w[1001];
int s[1001];
int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> w[i];
    }
    int ans = 0;
    sort(w + 1, w + 1 + n);
    int j = 0;
    for(int i = 1; i <= n; i++){
        j++;
        if (j == m+ 1) j = 1;
        s[j] += w[i];
        ans += s[j];
    }
    
    cout << ans << endl;
    return 0;
}