/**

 * Definition for singly-linked list.

 * public class ListNode {

 *     public int val;

 *     public ListNode next;

 *     public ListNode(int val=0, ListNode next=null) {

 *         this.val = val;

 *         this.next = next;

 *     }

 * }

 */

public class Solution {

    public ListNode MergeNodes(ListNode head) {

        var x = head;

        while (x.next != null)

        {

            while (x.next.val != 0)

            {

                x.val += x.next.val;

                x.next = x.next.next;

            }

            x = x.next;

        }

        return head;

    }

}