import pyutil as pyu
pyu.get_local_pyinfo()

print(pyu.ps2("python-dotenv"))

from typing import List

class Solution:
  def deleteDuplicates(self, head: ListNode) -> ListNode:
    dummy = ListNode(0, head)
    prev = dummy

    while head:
      while head.next and head.val == head.next.val:
        head = head.next
      if prev.next == head:
        prev = prev.next
      else:
        prev.next = head.next
      head = head.next

    return dummy.next

new Solution().deleteDuplicates()