function nav_tab(n,showid,hideid,m){
	for(var i=1;i<=m;i++){
		var curC=document.getElementById(hideid+i);
		var curB=document.getElementById(showid+i);
		if(n==i){
			curC.style.display="block";
			curB.className="active"
		}else{
			curC.style.display="none";
			curB.className="normal"
		}
	}
}