/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/

public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode head = new ListNode(-1);
        ListNode p = head;
        int carry = 0;
        while(l1 != null || l2 != null){
            int result = 0;
            int va = (l1 == null)? 0: l1.val;
            int vb = (l2 == null)? 0: l2.val;
            result = (va+vb+carry)%10;
            carry = (va+vb+carry)/10;
            p.next = new ListNode(result);
            p = p.next;
            l1 = (l1 == null ? null : l1.next);
            l2 = (l2 == null ? null : l2.next);
        }
        
        if(carry != 0){
            p.next = new ListNode(carry);
        }
        
        return head.next;
    }
}