# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    # 返回ListNode
    def ReverseList(self, pHead):
        # write code here
        back = None
        forward = None
        while(pHead):
            forward = pHead.next
            pHead.next = back
            back = pHead
            pHead = forward
        pHead = back
        return pHead