function addButton(counter)
{
   // pobiera div id="buttons" 
   box = document.getElementById("buttons");
   
   // dodaje HTML do div id="buttons" 
   div = document.createElement('div');
   div.innerHTML = '<input type="button" value="'+(counter+1)+'. Add new button" name="myButton'+(counter+1)+'" onclick="addButton('+(counter+1)+'); this.disabled = true;" />';
   
   box.appendChild(div);
}