#include<bits/stdc++.h>
using namespace std;
long long n,r;
long long a[1000];
long long b[1000];
long long ans;
int main(){
    cin>>n>>r;
    for(int i=1;i<=n;i++){
    	cin>>a[i];
    }
    sort(a+1,a+n+1);
    for(int i=1;i<=n;i++){
    	if(i<=r){
    		b[i]=a[i];
    	}else{
    		b[i]=a[i]+a[i-r];
    	}
    	ans=ans+b[i];
    }
    cout<<ans<<endl;
	return 0;
}

/**************************************************************
	Problem: 1228
	User: zengdongxin
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2092 kb
****************************************************************/