Given a singly linked list, find middle of the linked list. Assume that the list has no length variable.

For example, if the given linked list is 1->2->3->4->5 then output should be 3.

If there are even nodes, then there would be two middle nodes, we need to print second middle element.

For example, if given linked list is 1->2->3->4->5->6 then output should be 4.

For full credit your algorithm (C++ code) will run in T(n) = n/2.

For partial credit, your algorithm will run in T(n)= 2n, or T(n)= n+n/2 where n is the size of the list.