#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define MAX 100000
#define pb push_back
#define mp make_pair
#define INF (1LL<<62)
#define MOD 1000000007
typedef long long Int;
typedef pair<Int,Int> pii;
typedef vector<Int> vi;
typedef vector<pii> vii;

Int n,k,c[10010];
Int fun(Int i)
{
    if((i+k>n)||(i-k)<1)
        return 0;

    Int ans1=INF,ans2=INF;    
    for(Int j=i+1;j<=i+2*k+1;j++)
    {
        if(j<=n+1)
        ans1=min(ans1,fun(j)+c[j] );
    }
     for(Int j=i-1;j>=i-2*k-1;j--)
    {
        if(j>=0)
        ans2=min(ans2,fun(j)+c[j] );
    }
    return ans1+ans2;
}

int main() {
   
    cin>>n>>k;
    Int sum=0;
    
    for(int i=1;i<=n;i++)
    {
        cin>>c[i];
        sum+=c[i];
        
    }
    if(k==0)
    {
        cout<<sum<<endl;
        return 0;
    }
    
    Int ans=INF;
    c[0]=0;
    c[n+1]=0;
    for(int i=1;i<=n;i++)
    {
        ans=min(c[i]+fun(i),ans);
        
    }
    cout<<ans;
    
    return 0;
}