Maximum Festive Gift Path

Description

You are walking along a snowy Christmas lane lined with $N$ gift stations. Each station $i$ contains a gift with value $A[i]$ (some gifts are bad… they can be negative).

You start at station 1 and want to reach station $N$. From station $i$, Santa allows you to jump forward to any station $j$ such that:
$i < j \le i + K$

Each time you land on a station, you collect the gift there.

Your goal: Collect the maximum total gift value possible from station $1 \to$ station $N$.

Input Specification

• The first line contains two integers $N$ and $K$.
  • $1 \le N \le 2 \times 10^5$
  • $1 \le K \le 10^5$
• The second line contains $N$ integers $A[i]$, representing the gift values at each station.
  • $|A[i]| \le 10^9$

Output Specification

Print a single integer — the maximum total gift value you can gather on your journey to the final station.

Sample Cases

Sample Input

Sample Output