Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only *distinct* numbers from the original list.

For example,

Given `1->2->3->3->4->4->5`

, return `1->2->5`

.

Given `1->1->1->2->3`

, return `2->3`

.

**Naive O(n) space complexity.**

**O(1) Space complexity**