function cambia() {
	att= document.getElementById('attNews').value;
	if (!att || att==null || att=="") {att=0;}
	if (att < document.getElementById('numNews').value) {
		prox= att;
		prox++;
	}
	else prox=0;
	
	idAtt="news"+att;
	idProx="news"+prox;
	
	document.getElementById(idAtt).style.display="none";
	
	if (document.getElementById(idAtt).style.display=="none") {document.getElementById(idProx).style.display="block";}
	
	document.getElementById('attNews').value=prox;
}