if (document.images)
  {
  preload("about1","images/main/btn_about2.jpg");
  preload("about2","images/main/btn_about2_up.jpg");
  preload("diary1","images/main/btn_diary2.jpg");
  preload("diary2","images/main/btn_diary2_up.jpg");
  preload("lessons1","images/main/btn_lessons2.jpg");
  preload("lessons2","images/main/btn_lessons2_up.jpg");
  preload("livery1","images/main/btn_livery2.jpg");
  preload("livery2","images/main/btn_livery2_up.jpg");
  preload("activities1","images/main/btn_activities2.jpg");
  preload("activities2","images/main/btn_activities2_up.jpg");
  preload("contact1","images/main/btn_contact2.jpg");
  preload("contact2","images/main/btn_contact2_up.jpg");
  }