# Definition for singly-linked list.
# class ListNode(object):
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution(object):
def deleteDuplicates(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
dummy=cur=ListNode(0)
dummy.next=head
while head and head.next:
if head.val==head.next.val:
while head and head.next and head.val==head.next.val:
head=head.next
head=head.next
cur.next=head
else:
cur.next=head
cur=cur.next
head=head.next
return dummy.next
