Electricity

/*
    Task    : _example
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 21 December 2022 [21:15]
*/
#include<bits/stdc++.h>
using namespace std;
struct A{
    int val,idx;
    bool operator < (const A&o) const{
        return val>o.val;
    }
};
priority_queue<A > heap;
int dp[500010];
int main(){
    int n,k;
    scanf("%d %d",&n,&k);
    for(int i=1;i<=n;i++){
        scanf("%d",&dp[i]);
        if(heap.empty()){
            heap.push({dp[i],i});
            continue;
        }
        // i <-> heap.top().idx
        while(!heap.empty() && i-heap.top().idx>k)
            heap.pop();
        dp[i]+=heap.top().val;
        heap.push({dp[i],i});
    }
    printf("%d\n",dp[n]);
    return 0;
}