function foco(elemento,id) { 
	var noteid = 'note' + id;  
	document.getElementById(noteid).style.display="none";	
} 


function validar(formulario) {
	var contret=0;

	if (formulario.usuario.value.length =="") { 
		document.getElementById("noteusuario").style.display="block";
		contret = contret+1;		
	}
	else{
		document.getElementById("noteusuario").style.display="none";
	}	

	if (formulario.pass.value.length =="") { 
		document.getElementById("notepass").style.display="block";
		contret = contret+1;
	}
	else{
		document.getElementById("notepass").style.display="none";
	}

   
   if(contret!=0){
	return (false);
	}
  
}