# Definition for singly-linked list.

# class ListNode(object):

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution(object):

    def removeNthFromEnd(self, head, n):

        """

        :type head: ListNode

        :type n: int

        :rtype: ListNode

        """

        dummy=ListNode(0)

        dummy.next=head

        p1=p2=dummy

        for i in range(n):

            p1=p1.next

        while p1.next:

            p1=p1.next

            p2=p2.next

        p2.next=p2.next.next

        return dummy.next