using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        // 163 + 458 =  621

        Node first = new Node(3);

        first.next = new Node(6);

        first.next.next = new Node(1);

        Node second = new Node(8);

        second.next = new Node(5);

        second.next.next = new Node(4);

        Node result = Add(first, second, 0);

        while(result!=null){

            Console.Write(result.val);

            result = result.next;

        }

    }

    public static Node Add(Node list1, Node list2, int carry){

        int sum = carry;

        if(list1 != null) sum+= list1.val;  

        if(list2 != null) sum+= list2.val;

        Node thisPosition = null;

        if(sum > 0){

            int ones = sum % 10;

            thisPosition = new Node(ones);

            carry = sum / 10;

            thisPosition.next = Add(list1.next, list2.next, carry);

        }

        return thisPosition;

    }

    public class Node{

        public int val;

        public Node next;

        public Node(int x){

            val = x;    

        }   

    }

}