# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution:
    def reverseList(self, head: ListNode) -> ListNode:
        if head:
            aux = head
            while aux.next:
                curr = aux.next
                aux.next = curr.next
                curr.next = head
                head = curr

            return head