function switchtab(num){
	for(var i=0;i<4;i++){
	  if(i==num){
		document.getElementById("z"+num).className="nselected";
		document.getElementById("zw"+num).style.display="block";
	  }else{
		  document.getElementById("z"+i).className="ttz";
		document.getElementById("zw"+i).style.display="none";
	  }
	}
	
}

function ntab(num){
  	 if(num==0){
		document.getElementById("y0").className="yqtab1"; 
		document.getElementById("yc0").style.display="block";
		document.getElementById("y1").className="yqtab2"; 
		document.getElementById("yc1").style.display="none";
	 }else{
		 document.getElementById("y0").className="yqtab3"; 
		document.getElementById("yc0").style.display="none";
		document.getElementById("y1").className="yqtab4"; 
		document.getElementById("yc1").style.display="block";
	 }
}