#include<bits/stdc++.h>
using namespace std;
priority_queue<int, vector<int>, greater<int> > q;
int main()
{
	int n, m, w, ans = 0;
	cin >> n >> m;
	while(n --)
	{
		cin >> w;//依次读入n个人的接水时间
		int tmp = q.top() + w;
		ans = max(ans, tmp);
		if(q.size() >= m)
			q.pop();//锁定大小
		q.push(tmp);
	}
	cout << ans;
	return 0;
}