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

class Solution(object):
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        return self.linkedlist(self.number(l1) + self.number(l2))
    def linkedlist(self, number):
        if not number: return ListNode(0)
        head = ListNode(0)
        while number:
            head.next, head.next.next = ListNode(number % 10), head.next
            number /= 10
        return head.next
    def number(self, l1):
        n = 0
        while l1:
            n = n*10 + l1.val
            l1 = l1.next
        return n