/**
 * Definition for ListNode
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param ListNode head is the head of the linked list
     * @return: ListNode head of the linked list
     */
    public static ListNode deleteDuplicates(ListNode head) {
        // write your code here
        if(head==null){
			return null;
		}
		LinkedHashMap<Integer,Integer> map=new LinkedHashMap<Integer,Integer>();
		map.put(head.val, 1);
		while(head.next!=null){
			head=head.next;
			if(map.containsKey(head.val)){
				map.put(head.val, map.get(head.val)+1);
			}else{
				map.put(head.val, 1);
			}
		}
		
		Set<Integer> ts= map.keySet();
		Iterator<Integer> it=ts.iterator();
		ArrayList<Integer> list=new ArrayList<Integer>();
		while(it.hasNext()){
			int temp=it.next();
			if(map.get(temp)==1){
				list.add(temp);
			}
		}
		if(list.size()==0){
		    return null;
		}
		ListNode newHead=new ListNode(list.get(0));
		ListNode node=newHead;
		for(int i=1;i<list.size();i++){
			node.next=new ListNode(list.get(i));
			node=node.next;
		}
		return newHead;

    }
}