private Node Insert(Node p, int val)
 {
     if (p == null)
     {
         Node q = new BsTreeAvlCopy(val);
         q.height = 1;
         return(q);
     }
     if (val < p.val)
     {
         p.left = Insert(p.left, val);
     }
     else
     {
         p.right = Insert(p.right, val);
     }
     return(Balance(p));
 }