function std_nav_show(id,celkem) {
  for(i=0;i<celkem;i++) {
     try {
          document.getElementById('std_nav_name_'+i).className='std_nav_name';
          document.getElementById('std_nav_body_content_'+i).className='std_nav_hidden';
        } catch(e) {
        };
  };
  document.getElementById('std_nav_name_'+id).className='std_nav_name std_nav_name_selected';
  document.getElementById('std_nav_body_content_'+id).className='std_nav_body_content_selected';
}