Electricity

/*
    Task    : Electricity
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 12 December 2022 [21:45]
*/
#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(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int n,k;
    cin >> n >> k;
    for(int i=1;i<=n;i++){
        cin >> dp[i];
        if(heap.empty()){
            heap.push({dp[i],1});
            continue;
        }
        while(!heap.empty() && i-heap.top().idx > k)    heap.pop();
        dp[i]+=heap.top().val;
        heap.push({dp[i],i});
    }
    cout << dp[n];
    return 0;
}