public class Tree {
   int node;
   Tree upper;
 
   
   public Tree()
   {
	   node=-1;
	   upper=null;	   	   
   }
     
   public void UnionTree(Tree tree1,Tree tree2)
   {
	   node=tree1.node;
	   tree1.upper=this;
	   tree2.upper=this;	   
   }
}