# 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:
        number1 = ""
        number2 = ""
        output_number = None

        while(l1 is not None):
            number1 = "{}{}".format(l1.val, number1)
            l1 = l1.next

        while(l2 is not None):
            number2 = "{}{}".format(l2.val, number2)
            l2 = l2.next

        # print("number1 is {}".format(number1))
        # print("number2 is {}".format(number2))

        output_number = int(number1) + int(number2)
        output_str = str(output_number)

        # print("output_number is {}".format(output_number))

        output_ll = None
        next = None
        for count, i in enumerate(reversed(range(0, len(output_str)))):
            digit = output_str[i]
            # print("digit is {}".format(digit))
            # print("count is {}".format(count))
            if(count == 0):
                next = ListNode(digit)
                output_ll = next
            else:
                next.next = ListNode(digit)
                next = next.next

        return output_ll