#include <fstream>
#include <algorithm>

using namespace std;

ifstream f("transport.in");
ofstream g("transport.out");

int v[16001];

int main()
{
    int i, n, k, maxim, j = 1, s = 0;

    f >> n >> k;

    for(i = 0; i < n; i++)
        f >> v[i];

    sort(v, v + n);

    maxim = v[n - 1];

    for(i = n - 1; i >= 0; i--)
    {
        k = (n - i - 1) % j;
        if(k == 0)
            {
            if(s > maxim)
                maxim = s;
            j++;
            s = 0;
            }
        else
                s += v[i];
    }

    g << maxim;

    f.close();
    g.close();

    return 0;
}