public boolean cumple ()
    	{Queue<Character> caux1= new colaArregloCircular<Character>();
    	Stack<Character> p= new ArrayStack<Character>();
	    PositionList <Character> aux=new NodePositionList<Character>();
		boolean exp=true;
		try{
			Position<Character> pos= log.first();
			while(pos!=log.last())
				{aux.addLast(pos.element());
				pos=log.next(pos);}
				aux.addLast(pos.element());
				Position<Character> actual= aux.first();

				char ch=actual.element();

				int i=1;
				while(i<aux.size() && exp)
					{while(i<aux.size() && (ch != 'x'))
						{caux1.enqueue(ch);
						p.push(ch);
						actual=aux.next(actual);
						ch=actual.element();
						i++;
						}

					if(i>aux.size())
						exp=false;
					else
						{if (controlarCola(caux1))
							{while (!p.isEmpty() && exp)
								{actual=aux.next(actual);
								ch=actual.element();
								char ch2=p.pop();
								i++;
								if(ch==ch2)
									{}
								else exp=false;}
							}

						else exp=false;
						}

					if( i<aux.size())
						{actual=aux.next(actual);
						ch=actual.element();
						i++;
						if(ch=='x' && i<aux.size())
							{actual=aux.next(actual);
							ch=actual.element();
							i++;}
						else exp=false;
						}
					}
	   	     return exp;}

		catch (TDAPila.EmptyStackException e)
			{System.out.println(e.getMessage());}
		catch (InvalidPositionException e)
			{System.out.println(e.getMessage());}
		catch (EmptyListException e)
			{System.out.println(e.getMessage());}
		catch (BoundaryViolationException e)
			{System.out.println(e.getMessage());}
	    return exp;
	   }


    /**
     * Es un metodo privado que consulta si la cola pasada por parametro
     * cumple con el formato CzCC
     *
     * @param c Cola de caracteres.
     *
     * @return Verdadero si cumple, en caso contrario retorna falso.
     */
    private static boolean controlarCola(Queue<Character> c)
    	{Queue<Character> caux= new colaArregloCircular<Character>();
    	int cant=0;
    	int i=0;
    	boolean control=true;
    	try{
    		char ch=c.dequeue();
    		if (ch=='z' && cant==c.size())
    			control=true;
    		else
    			{while(ch!='z' && !c.isEmpty())
    				{caux.enqueue(ch);
    				ch=c.dequeue();
    				cant++;}
    			if(c.isEmpty())
    				control=false;
    			else
    				{while( i<= 2*cant && !c.isEmpty() && control)
    					{ch=c.dequeue();
    					char chaux= caux.dequeue();
    					if(ch==chaux)
    						{i=i+1;
    						caux.enqueue(chaux);}
    					else control=false;
    					}

    				if (i!=cant*2)
    					control=false;
    				}
    			}
    		return control;}

    	catch (EmptyQueueException e)
    		{System.out.println(e.getMessage());}

    	return control;}