function refbox() {
	var limit = document.getElementById('reflimit').value;
	for(i=1;i<=limit;i++){
		document.getElementById('dn'+i).style.display='none';				
	}
	
	var c=Math.round(Math.random() * (limit - 1) + 1)
	
	document.getElementById('dn'+c).style.display='block';
	setTimeout("refbox()", 10000);
}