#include<stdio.h>
#include<stdlib.h>

#include<set>
#include<algorithm>

using namespace std;

#define MAXN 5000000

int V[MAXN];

struct ComparePair {
    bool operator() (const std::pair<int,int> & p1, const std::pair<int,int> & p2) const {
		if(p1.first == p2.first)
			return (p1.second < p2.second);
		else
			return (p1.first < p2.first);
    }
};

set<pair<int,int>,ComparePair> multime;

int N, K;
long long rez;

void findsum(){
	rez+=(long long)(multime.begin()->first);
	set<pair<int,int>,ComparePair>::iterator it;
	for(int i=K; i<N; i++){
		pair<int,int> p(V[i-K],i-K);
		it=multime.find(p);
		multime.erase(it);
		multime.insert(make_pair(V[i],i));
		rez+=(long long)(multime.begin()->first);
	}
}

int main(){
	
	freopen("deque.in","rt",stdin);
	freopen("deque.out","wt",stdout);
	
	scanf("%d %d",&N,&K);

	for(int i=0;i<N;i++){
		scanf("%d",&V[i]);
		if(i<K)
			multime.insert(make_pair(V[i],i));
	}
	
	findsum();

	printf("%lld",rez);

	return 0;
}