var obj_img=document.getElementById("imgarea");
var obj_txt=document.getElementById("txtarea");
var timeout=-1;
var arr=[];
arr[0]=59;
function changeimg(where){
	var i=obj_img.src.split("/")[6].split(".")[0];
	i=Number(i);
	i+=where;
	if(i>arr[0])i-=arr[0];
	if(i<1)i+=arr[0];
	obj_img.src="http://50th.ustc.edu.cn/anniversary/souvenirs/images/"+i+".png";
	obj_txt.innerHTML="loading...";
	clearTimeout(timeout);
	timeout=setTimeout('obj_txt.innerHTML="?????'+i+'/'+arr[0]+'";',3000);
}