# Definition for singly-linked list.

# class ListNode:

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution:

    def deleteDuplicates(self, head: ListNode) -> ListNode:

        p = head

        while p and p.next:

            if p.val == p.next.val:

                p.next = p.next.next

            else:

                p = p.next

        return head