//You are given an array of N integers (both positive and negative). 
//You can either take an element and add it to your sum or skip it. 
//However, if you take an element, you must skip the next K elements.
//Find the maximum sum you can obtain.
#include <bits/stdc++.h>
using namespace std;
 
int main() {
	int n,k;cin>>n>>k; int arr[n];
	for(int i=0;i<n;i++)
	cin>>arr[i];
 
	vector<int>dp(n,0);
	dp[0]=arr[0];
	for(int i=1;i<=k;i++)
	dp[i]=max(arr[i], dp[i-1]);
	for(int i=k+1;i<n;i++){
		dp[i]=max(arr[i]+dp[i-k-1], dp[i-1]);
	}
	cout<<dp[n-1]<<endl;
	return 0;
}

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MTUKNAoyCi01CjgKNAo5CjEyCi04Ci0yCjQKLTEKNgo4Ci05CjQKNw==

15
4
2
-5
8
4
9
12
-8
-2
4
-1
6
8
-9
4
7