#include<bits/stdc++.h>
using namespace std;

#define MAX 10009
#define ll long long

int mark[MAX],color[MAX];
ll arr[MAX];

int main(){
	int n,k,i,j,r;
	cin>>n>>k;
	for(i=0;i<n;++i) cin>>arr[i];
	int SETSIZE=1;
	for(i=1;i<=n;++i) SETSIZE*=2;
	ll ans=1e18;
	for(i=0;i<SETSIZE;++i){
		if(i==0) continue;
		memset(mark,0,sizeof(mark));
		for(j=0;j<n;++j){
			if(i&(1<<j))
				mark[j]=1;
		}
		//for(j=0;j<n;++j) printf("H%d ",mark[j]); printf("\n");
		memset(color,0,sizeof(color));
		for(j=0;j<n;++j){
			if(mark[j]){
				//cout<<j<<endl;
				color[j]=1-color[j];
				for(r=j-1;r>=0&&r>=(j-k);--r){
					color[r]=1-color[r];
				}
				for(r=j+1;r<n&&r<=(j+k);++r){
					color[r]=1-color[r];
				}
			}
		}
		//for(j=0;j<n;++j) printf("I%d ",color[j]); printf("\n\n");
		int flag=0;
		for(j=0;j<n;++j){
			if(!color[j])
				flag=1;
		}
		if(!flag){
			ll sum=0;
			for(j=0;j<n;++j){
				if(mark[j])
					sum=sum+arr[j];
			}
			ans=min(ans,sum);
		}
	}
	printf("%lld\n",ans);
	return 0;
}