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