electricity

#include<stdio.h>
#include<queue>
using namespace std;

int arr[500010];
int dp[500010];

int n,k;
int min(int a,int b){
    return (a < b ? a : b);
}
/*
int cal(int I){
    if(I == n)return arr[I];
    if(dp[I])return dp[I];
    int ans = 1e9+1;
    for(int i = I + 1 ; i <= I + k && i <= n ; i ++){
        ans = min(ans,cal(i));
    }
    return dp[I] = ans + arr[I];
}*/
int main()
{
    scanf("%d %d",&n,&k);
    for(int i = 1 ; i <= n ; i ++){
        scanf("%d",&arr[i]);
    }

//  printf("%d",cal(1));
    priority_queue<pair<int,int> ,vector<pair<int,int> > ,greater<pair<int,int> > > pq;
    dp[n] = arr[n];
    for(int I = n - 1; I >= 1; I --){
        while(!pq.empty() && pq.top().second > I + k)pq.pop();
        pq.push({dp[I+1],I+1});
        dp[I] = pq.top().first + arr[I];
    }
    printf("%d",dp[1]);
    return 0;
}