function setTab(nav,what,con,box,n){
 var tli=document.getElementById(nav).getElementsByTagName(what);
 var mli=document.getElementById(con).getElementsByTagName(box);
 for(i=0;i<tli.length;i++){
  tli[i].className=i==n?"select":"";
  mli[i].style.display=i==n?"block":"none";
 }
}