function podmientlo (podm_klas, id, srodek_id){

    var elem = document.getElementById(id);
    var elem2 = document.getElementById(srodek_id);    
    var licz = elem.getElementsByTagName("li"); 

    for( var i=0; i<licz.length; i++) {
      var pom = i+2;
      elem.getElementsByTagName("li")[i].className = 'r'+pom ;
      if ( elem.getElementsByTagName("li")[i].className == podm_klas ) { elem.getElementsByTagName("li")[i].className = 's'+ podm_klas; }
    
    }   
    
    document.getElementById('srodek2').style.display = 'none';
    document.getElementById('srodek3').style.display = 'none';
    document.getElementById('srodek4').style.display = 'none';
 
    document.getElementById(srodek_id).style.display = 'block';
    return true;
}