public static void DeleteNode(ListNode1 node)
 {
     if (node.next != null)
     {
         node.val  = node.next.val;
         node.next = node.next.next;
     }
     node = null;
 }
        public static void OnMain()
        {
            var node1 = new ListNode1(4);
            var node2 = new ListNode1(2);
            var node3 = new ListNode1(3);
            var node4 = new ListNode1(4);
            var node5 = new ListNode1(5);

            node1.next = node2;
            node2.next = node3;
            node3.next = node4;
            node4.next = node5;
            node5.next = null;
        }