function switch_langc() {
 var selfUrl = top.location.href; //current path
 gurl = "http://www.vitasoy.com.hk"
 //myglength = gurl.length //url path length
 myglength = gurl.length 
 myslength = selfUrl.length // current path length
 targetUrl = selfUrl.substring(myglength+4,selfUrl.length-5); // get the file name
 targetUrl = gurl + "/chi" + targetUrl + ".html" //gen the new file name

top.location.href = targetUrl;
//alert(selfUrl);
}