/*
  Reverse a linked list and return pointer to the head
  The input list will have at least one element
  Node is defined as
  class Node {
     int data;
     Node next;
  }
*/

Node Reverse(Node head) {
    if(head == null || head.next == null)
        return head;

    Node p = null;
    Node tail= null;

    while(head != null){
        p = head.next;
        head.next = tail;
        tail = head;
        head = p;
    }

    return tail;
}