#include<bits/stdc++.h>
using namespace std;
int n,r,a[501],b[101][501],k,d=1,ans;
int main(){
    cin>>n>>r;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    } 
    sort(a+1,a+n+1);
    for(int j=1;j<=n;j++){
        k++;    
        if(k>r){
        k=k-r;  
        d++;
        }
        b[k][d]=a[j]+b[k][d-1]; 
         
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=d;j++){
            ans+=b[i][j];
        }
    }
    cout<<ans;
    return 0;
}
/**************************************************************
	Problem: 1228
	User: wengsihan
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2276 kb
****************************************************************/