public void deleteByMerging(int el){IntBSTNode tmp,node,p=root,prev=null;/*find the node to be deleted*/while(p!=null&&p.key!=el){prev=p;if(p.key<el)p=p.right;else p=p.left;}/*find end*/node=p;if(p!=null&&p.key==el){if(node.right==null)//node has no right child then its left child (if any) is attached to node=node.left;//its parent  else if(node.left==null)  //node has no left child then its right child (if any) is attched to  node=node.right  //its parentelse{tmp=node.left;  while(tmp.right!=null)tmp=tmp.right;//find the rightmost node of the left subtreetem.right=node.right;//establish the link between the rightmost node of the left subtree and the right subtreenode=node.left;}if(p==root){root=node;}else if (prev.left==p){prev.left=node;}else prev.right=node}else if(root!=null)  {System.out.println("the node is not in the tree");}else System.out.println("The tree is empty");}