using System;
using System.Collections.Generic;

/*
public class ListNode
{
    public int val;
    public ListNode next;

    public ListNode (int x)
    {
        val = x;
    }
}
*/

class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        // write code here
        if (head == null)
            return head;
        ListNode listNode = head;
        ListNode listNodeRtn = head;
        int nVal = head.val;
        head = head.next;
        while (head != null) {
            if (!head.val.Equals(nVal)) {
                nVal = head.val;
                head = head.next;
                listNode = listNode.next;
                continue;
            }
            listNode.next = head.next;
            head = listNode.next;
        }
        return listNodeRtn;
    }
}