Given the head of a linked list, return the list after sorting it in ascending order.

Follow up: Can you sort the linked list in O(n log n) time and O(1) memory (excluding recursive stack space)?

Example 1:

Input: 4 2 1 3
Output: 1 2 3 4

Example 2:

Input: -1 5 3 4 0
Output: -1 0 3 4 5

Input format: Single line of space-separated integers.

Output format: Sorted list.