#include<stdio.h>
int A[5000001], i, cap, coada, k, s, n;
long long D[5000001];
int main()
{freopen("deque.in","r",stdin);
freopen("deque.out","w",stdout);
scanf("%d%d", &n, &k);
	cap=1 ; coada=0;
	 for(i=1 ; i<=n ; i++) scanf("%d", &A[i]);
	 while 
		(cap<=coada && A[i]<=A[D[coada]]) coada--;
	A[++coada ]=i;
	if (D[cap]==i-k);cap++ ;
	if (i>=k) s+=A[D[cap]] ; 
	printf ("%lld", s);\
	return 0 ;
	}