#include <fstream>
#include <vector>
#include <unordered_map>
#include <algorithm>
#include <utility>
using namespace std;

ifstream in ("deque.in");
ofstream out("deque.out");

vector<int>* getAllPositions(const unordered_multimap<int, int>& myHash, int minim)
{
	vector<int> *pozitii = new vector<int>;
	unordered_multimap<int, int>::const_iterator it = myHash.find(minim);
	
	while (it->first == minim)
	{
		pozitii->push_back(it->second);
		++it;
		if (it == myHash.end())
			break;
	}

	// oare mere mai bine in heap ?
	return pozitii;
}

int v[5000001];
int main()
{
	int n, k; in >> n >> k;

	unordered_multimap<int, int> myHash;
	for (int i = 1; i <= n; ++i)
	{
		in >> v[i];
		myHash.insert(make_pair(v[i], i));
	}
	
	vector<int> heap;
	for (int i = 1; i <= k; ++i)
		heap.push_back(-v[i]);
	make_heap(heap.begin(), heap.end());

	long long suma = 0;
	suma += -heap[0];

	for (int i = k + 1; i <= n; ++i)
	{
		heap.push_back(-v[i]);
		push_heap(heap.begin(), heap.end());
		
		bool ok = false;
		while (ok == false)
		{
			int minim = -heap[0];
			vector <int> *pozitiiAleMinimului = getAllPositions(myHash, minim);

			bool exista = false;
			for (vector<int>::iterator it = pozitiiAleMinimului->begin();
				it != pozitiiAleMinimului->end();
				++it)
				if (*it >= i - k + 1 && *it <= i)
				{
					exista = true;
					ok = true;
					break;
				}
				
				delete pozitiiAleMinimului;
				
				if (exista == true)
					suma += minim;
				else
					pop_heap(heap.begin(), heap.end()), heap.pop_back();
		}
	}

	out << suma;

	return 0;
}