/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {


        ListNode* x = new ListNode(0);
        ListNode* curr = x;
        ListNode* h1 = l1;
        ListNode* h2 = l2;

        int c = 0;
        while(h1 || h2 || c )
        {
            if (h1)
            {
                c += h1->val;
                h1 = h1->next;
            }

            if (h2)
            {
                c += h2->val;
                h2 = h2->next;
            }
            curr -> next = new ListNode( c % 10 );
            curr = curr -> next;
            c /= 10;
        }

        x = x -> next;
        return x;


    }
};

/*
 342 + 465 = 807.

 3 4 2
 4 6 5
 -------
  7 0 8

*/