#include<bits/stdc++.h>
using namespace std;
int n,r,a[1000],b[1000],s=0;
int main(){
cin>>n>>r;
for(int i=1;i<=n;i++)cin>>a[i];
sort(a+1,a+1+n);
for(int i=1;i<=n;i++){
    b[i]=a[i];
    if(i>=r+1){
        b[i]=b[i]+b[i-r];
    }
    s=s+b[i];
}
    cout<<s;
}
/**************************************************************
	Problem: 1228
	User: chenruhong
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2084 kb
****************************************************************/