Reverse in groups of k

Problem

Reverse the nodes of a linked list k at a time and print the result. If fewer than k nodes remain at the end, leave them as they are.

Input: Line 1: integers separated by spaces. Line 2: k.
Output: The list after reversing each full group.
Constraints: 1 ≤ number of values ≤ 10000
1 ≤ each value ≤ 1000000000
1 ≤ k ≤ 10000

Example 1

Input

1 2 3 4 5
2

Output

2 1 4 3 5

Example 2

Input

1 2 3 4 5
3

Output

3 2 1 4 5

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

Hint 1

For each group, check that k nodes exist before touching any link.

Hint 2

Reverse the group, then join it to the group before and after it.

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