cs=0;
var timeshow;
function change(divname,a)
{ 
  var divarray=document.getElementById("mynav").getElementsByTagName("div");
  var aarray=document.getElementById("mynav").getElementsByTagName("a");
  for(i=0;i<divarray.length;i++)
  {
     divarray[i].style.display="none";
	 aarray[i].className="";
  }
  document.getElementById(divname).style.display="block";
  a.className="now";
}