function activetab(n,z) {
  var numtabs = z;
  for(a=0;a<numtabs;a++){
    if(n==a) {
      var curtab = document.getElementById("nav"+a);
      curtab.className="here"
      var showtab = document.getElementById("tab"+a);
      showtab.style.display = "";
    } else {
      var curtab = document.getElementById("nav"+a);
      curtab.className=""
      var showtab = document.getElementById("tab"+a);
      showtab.style.display = "none";
    }
  }
}