#include <bits/stdc++.h>
#define ll long long
#define pb push_back
using namespace std;
const int N=100011;
int q,n,x,y,k,arr[N];
string s;
ll dp[10001][1001];
ll solve(int i,int prvk,int BeforCnt )
{
    if(i>n)
    {
        if(BeforCnt==0) return 0;
        else    return 1e14;
    }
    if(BeforCnt>k)  return 1e14;
    ll &ret=dp[i][prvk];
    if(ret!=-1) return ret;
    ret=solve(i+1,prvk,BeforCnt+1);
    return ret=min(ret,arr[i]+solve(i+k+1,i,0));
}
int main(){
    cin>>n>>k;
    for(int i=0 ; i<n ; i++)
        cin>>arr[i];
    memset(dp,-1,sizeof(dp));
    cout<<solve(0,0,0)<<endl;

}