/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        
        if(l1==null)
            return l2;
        
        if(l2==null)
            return l1;

        ListNode res=l1.val<l2.val ? l1:l2;

        res.next=mergeTwoLists(res.next, l1.val>=l2.val ? l1:l2);

        return res;
    }
}