# Definition for singly-linked list.

# class ListNode:

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution:

    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:

        cur_l1 = l1

        cur_l2 = l2

        cur = ListNode(0)

        head = cur

        flag = 0

        while cur_l1 != None or cur_l2 != None:

            value = 0

            value += flag

            if cur_l1 != None:

                value += cur_l1.val

            if cur_l2 != None:

                value += cur_l2.val

            new_node = ListNode(0)

            cur.next = new_node

            cur = cur.next

            cur.val = value % 10

            flag = value // 10

            if cur_l1 != None:

                cur_l1 = cur_l1.next

            if cur_l2 != None:

                cur_l2 = cur_l2.next

        if flag != 0:

            new_node = ListNode(0)

            cur.next = new_node

            cur = cur.next

            cur.val = flag

        return head.next