function countLevels() {
                  var i = 0;
                  var last = -1;
                  for(i=0;i<elements.length;i++) {
                      if(elements[i].startLevel != -1) {
                          if(elements[i].startLevel > last) {
                              last = elements[i].startLevel;
                          }
                      }
                      if(elements[i].endLevel != -1) {
                          if(elements[i].endLevel > last) {
                              last = elements[i].endLevel;
                          }
                      }
                  }
                  //lastLevel = -1;
                  lastLevel = last;
                  lastLevel_changed = last;
              }