function changeRole(select) {
   if (select.selectedIndex != 0) {
       id("seminar").style.backgroundColor = "gray";
       id("seminar").disabled = true;
   } else {
       id("seminar").style.backgroundColor = "white";
       id("seminar").disabled = false;
   }
}

function changeSeminar(select) {

   if (select.selectedIndex != 0) {
       id("role").style.backgroundColor = "gray";
       id("role").disabled = true;
   } else {
       id("role").style.backgroundColor = "white";
       id("role").disabled = false;
   }
}

function id(id) {
   return document.getElementById(id);
}