#include<fstream>
using namespace std;
long long s=0,v[5000001],w[5000001], p=0,k;
void add(long long x,long long i )
{
	v[++p]=x;
	w[p]=i;
	long long t=p,t2=t/2,t3;
	if(t/2>0)while(v[t]<v[t/2])
	{
		v[t]=v[t2]+v[t];
		v[t2]=v[t]-v[t2];
		v[t]=v[t]-v[t2];
		w[t]=w[t2]+w[t];
		w[t2]=w[t]-w[t2];
		w[t]=w[t]-w[t2];
		t=t2;t2=t2/2;
		if(t2<=0)break;
	}
	while(w[1]<=i-k)
	{
		v[1]=v[p];
		w[1]=w[p];
		p--;t=1;t3=2*t;
		if(t3+1<=p)
		while(v[t]>v[t3]||v[t]>v[t3+1])
			if(v[t3]<v[t3+1])
			{	v[t]=v[t]+v[t3];
			    v[t3]=v[t]-v[t3];
				v[t]=v[t]-v[t3];
				w[t]=w[t]+w[t3];
			    w[t3]=w[t]-w[t3];
				w[t]=w[t]-w[t3];
				t=t3;t3=t3*2;
				if(t3+1>p)break;
			}
			else
			{	v[t]=v[t]+v[t3+1];
			    v[t3+1]=v[t]-v[t3+1];
				v[t]=v[t]-v[t3+1];
				w[t]=w[t]+w[t3+1];
			    w[t3+1]=w[t]-w[t3+1];
				w[t]=w[t]-w[t3+1];
				t=t3+1;t3=t*2;
				if(t3+1>p)break;
			}
		if(t3==p&&v[t]>v[t3])
			{	v[t]=v[t]+v[t3];
			    v[t3]=v[t]-v[t3];
				v[t]=v[t]-v[t3];
				w[t]=w[t]+w[t3];
			    w[t3]=w[t]-w[t3];
				w[t]=w[t]-w[t3];
				t=t3;t3=t3*2;
			}
	}
	if(i>=k)
	{
		s=s+v[1];
	}
}
int main()
{
	ifstream fcin("deque.in");
	ofstream fcout("deque.out");
	long long n,i,x;
	fcin>>n>>k;
	for(i=1;i<=n;i++)
		{fcin>>x;
		 add(x,i);
		 }
	fcout<<s<<'\n';
	return 0;
}