Remove Duplicates From Sorted List II

	/**
	 * 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.
	 * 
	 * */