#include <cstdio>
#include <deque>

using namespace std;

int main(){
	freopen("deque.in","rt",stdin);
	freopen("deque.out","wt",stdout);
	int n,k,t,sm=0;
	scanf("%u %u",&n,&k);
	deque<int>deq(k);
	for(int i=0;i<k;i++){
		scanf("%u",&deq[i]);
	}
	for(int i=k;i<=n;i++){
		int min=deq[0];
		for(int j=1;j<k;j++){
			if(deq[j]<min){
				min=deq[j];
			}
		}
		sm+=min;
		scanf("%u",&t);
		deq.pop_front();
		deq.push_back(t);
	}
	printf("%d",sm);
}