#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> P;
#define REP(i,n) for(ll i=0;i<ll(n);i++)













int main(void){
	cin.tie(nullptr);  ios_base::sync_with_stdio(false);
	ll i,j;





	ll N,M;
	cin >> N >> M;

	priority_queue<ll, vector<ll>, greater<ll>> q;
	REP(i,M) q.push(0);

	REP(i,N){

		ll t;
		cin >> t;

		ll x=q.top();
		q.pop();

		q.push(x+t);

	}


	ll mx=0;
	while(!q.empty()){

		ll x=q.top();
		q.pop();

		mx=max(mx,x);



	}



	cout << mx << endl;










	return 0;

}