var subs_array = new Array("sub1","sub2","sub3","sub4","sub5","sub6","sub7","sub8","sub9","sub10","sub11","sub12","sub13","sub14","sub15","sub16","sub17","sub18","sub19");



function displaySubs(the_sub){

	 if (document.getElementById(the_sub).style.display==""){

	   document.getElementById(the_sub).style.display = "none";return

  }

  for (i=0;i<subs_array.length;i++){

	   var my_sub = document.getElementById(subs_array[i]);

	   my_sub.style.display = "none";

	 }

  document.getElementById(the_sub).style.display = "";

}