Best stretch of fixed length

Problem

A website logs visitors per day. Find the largest total over any k consecutive days.

Example 1

Input

7 3
2 1 5 1 3 2 9

Output

3 + 2 + 9 = 14.

Example 2

Input

3 3
1 2 3

Output

Try the problem first. Open one hint at a time.

Hint 1

Find the total of the first k days, then slide one day at a time.

Hint 2

Add the new day and subtract the day that leaves.

Write your Python code, run it on the examples and submit it to hidden tests.