function randomize_sponsors(sponsors) {
  return sponsors.sort(randOrd);
}

function randOrd() {
  return (Math.round(Math.random())-0.5);
}

function vertical_ads(ads, display_number, div_id) {
	var str = '';
	str = generate_ads(ads, display_number, '<br><br>');
	document.getElementById(div_id).innerHTML = str;
}

function horizontal_ads(ads, display_number, div_id) {
	var str = '';
	str = generate_ads(ads, display_number, '&nbsp;&nbsp;');
	document.getElementById(div_id).innerHTML = str;
}

function generate_ads(ads, display_number, html_seperator) {
	var str = '';
	var rand_ads = randomize_sponsors(ads);
	if (rand_ads.length < display_number) {
		display_number = rand_ads.length;
	}
	for(var i=0; i < display_number; i++) {
		ad = randomize_sponsors(rand_ads[i]);
		str += "<a href='"+ad[0].link+"' target='new'><img style='border:0' src=" + ad[0].image + " /></a>";
		if (i+1 < display_number) {
			str += html_seperator;
		}
	}
	return str;
}