Given a Singly Linked List of size N, delete all alternate nodes of the list.

Example 1:

Input:
LinkedList: 1->2->3->4->5->6
Output: 1->3->5
Explanation: Deleting alternate nodes
results in the linked list with elements
1->3->5.

Example 2:

Input:
LinkedList: 99->59->42->20
Output: 99->42

Your Task:

Your task is to complete the function deleteAlt() which takes the head of the linked list in the input parameter and modifies the given linked list accordingly.

Constraints:
1<=N<=100

Expected Time Complexity: O(N).
Expected Auxiliary Space: O(1).