#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("transport.in");
ofstream fout("transport.out");
int n, v[16001],i,sum1=0,k,sum2=0;
int main()
{
    fin>>n>>k;
    for(i=1;i<=n;i++)
        fin>>v[i];
    sort(v+1,v+n+1);
    sum1=v[n];
    for(i=1;i<=n/k-1;i++)
        sum1+=v[i];
    for(i=n/2-k/2;i<=n/2+k/2;i++)
        sum2+=v[i];
    if(sum1>sum2)
        fout<<sum1;
    else
        fout<<sum2;
    return 0;
}