#include<fstream>
#include<iostream>

using namespace std;

int a[5000001],q[5000001],n,k,pr,ul,minim,poz,min1[5000001];
long long suma = 0;

void Citire()
{
	ifstream f ("deque.in");
	f>>n>>k;
	for (int i=1;i<=n;i++)
		f>>a[i];
	f.close();
}

int Minim(int x , int y)
{
	int i,minim1=q[x],pz=x;
	for (i=x;i<=y;i++)
		if (q[i]<minim1) {minim1=q[i];pz=i;}
	return pz;
}
void Deque()
{
	int i;
	pr=ul=1;
	minim=a[1];
	poz=1;
	for (i=1;i<=k;i++)
		{
			q[ul++]=a[i];
			if (minim>a[i]) {minim=a[i];poz=i;}
		}
	suma += minim;
	for (i=k+1;i<=n;i++)
	{
		if (a[i]<=minim) {q[ul++]=a[i];minim=a[i];poz=i;}
		else 
			{
				q[ul++]=a[i];
				if (poz==pr) 
					{
						poz=Minim(pr+1,ul-1);
						minim=q[poz];
						//min1[++pr] = minim;
					}
			}
		suma += minim; pr++;
	}
}

void Afisare()
{
	ofstream fout("deque.out");
	fout<<suma<<"\n";
	fout.close();
}

int main()
{
	Citire();
	Deque();
	Afisare();
	return 0;
}