# -*- coding:utf-8 -*-

# class ListNode:

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution:

    def FindKthToTail(self, head, k):

        # write code here

        l = []

        while head != None:

            l.append(head)

            head = head.next

        if k > len(l) or k < 1:

            return

        return l[-k]

# -*- coding:utf-8 -*-

# class ListNode:

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution:

    def FindKthToTail(self, head, k):

        # write code here

        if head == None or k == 0:

            return None

        pAhead = head

        pBehind = None

        for i in range(0,k-1):

            if pAhead.next != None:

                pAhead = pAhead.next

            else:

                return None

        pBehind = head

        while pAhead.next != None:

            pAhead = pAhead.next

            pBehind = pBehind.next

        return pBehind