#include<bits/stdc++.h>
using namespace std;
int main ()
{
	priority_queue<int,vector<int>,greater<int>> q;
	int n,m;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	{
		int x;
		cin>>x;
		if(q.size()==m)
		{
			int y=q.top()+x;
			q.pop();
			q.push(y);
		}
		else q.push(x);
	}
	while(q.size()>1)
	{
		q.pop();
	}
	cout<<q.top();
	return 0;
}