A conveyor belt scans n parcels in order. Parcel i has an integer weight (a weight may be negative, representing a rebate). You must choose a contiguous run of exactly k parcels and report the largest possible total weight over any such run.
Input format
Line 1: two integers n and k.
Line 2: n space-separated integers, the parcel weights.
Output format
A single integer: the maximum sum of any k consecutive parcel weights.
Constraints
- 1 ≤ k ≤ n ≤ 100000
- -1000 ≤ each weight ≤ 1000