class ListNode:

def __init__(self, val=0, next=None):

self.val = val

self.next = next

class Solution:

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

dummy = ListNode(0)

current = dummy

carry = 0

while l1 or l2:

x = l1.val if l1 else 0

y = l2.val if l2 else 0

total = carry + x + y

carry = total // 10

current.next = ListNode(total % 10)

current = current.next

if l1:

l1 = l1.next

if l2:

l2 = l2.next

if carry > 0:

current.next = ListNode(carry)

return dummy.next