(function(){
	shuffle = function(array) {
		var i = array.length;
		while(i){
			var j = Math.floor(Math.random()*i);
			var t = array[--i];
			array[i] = array[j];
			array[j] = t;
		}
		return array;
	}
	
	var ads = [{"src":"http:\/\/farm4.static.flickr.com\/3130\/2400619148_627ec92636_o.jpg","alt":"\u30a2\u30c0\u30eb\u30c8SNS","target":"_blank","url":"http:\/\/ad.heypo.com\/click\/200"},{"src":"http:\/\/farm3.static.flickr.com\/2186\/2400630358_d982024627_o.jpg","alt":"\u30b2\u30fc\u30e0\u306e\u3088\u3046\u306a\u51fa\u4f1a\u3044","target":"_blank","url":"http:\/\/ad.heypo.com\/click\/202"}];
	if (ads.length < 1) return;
	var ad = shuffle(ads).shift();
	document.getElementById('ad-zone-21').innerHTML = '<a href="' + ad.url +'" target="' + ad.target +'"><img src="' + ad.src +'" alt="' + ad.alt +'" /></a>';
})();