import java.util.*;
public class Stack2 implements Stack{
   Vector dati;
public Stack2(){
  dati = new Vector();
}
public void push(Object o)
{
  dati.addElement(o);
 
 }

public Object pop()
 throws StackException 
{
 if(dati.size() ==0) 
  throw new StackException("stack vuoto");
  int i = dati.size()-1;
  Object o = dati.elementAt(i);
  dati.removeElementAt(i);
 return o;
}

public Object top()
 throws StackException 
{
 if(dati.size() ==0) 
  throw new StackException("stack vuoto");
 return dati.elementAt(dati.size()-1);
}

public int size(){return dati.size();}
}