function werbung()
	{
	    if (nr == 1)
	    {
	       document.getElementById("werbung1").style.visibility = "visible";
	       document.getElementById("werbung2").style.visibility = "hidden";  
          document.getElementById("werbung3").style.visibility = "hidden"; 
          document.getElementById("werbung4").style.visibility = "hidden"; 
          document.getElementById("werbung5").style.visibility = "hidden";
	       nr = 2;
	    }
            else  
            if (nr == 2)
	    {
	       document.getElementById("werbung1").style.visibility = "hidden";
	       document.getElementById("werbung2").style.visibility = "visible";     
	       document.getElementById("werbung3").style.visibility = "hidden";
	       document.getElementById("werbung4").style.visibility = "hidden"; 
	       document.getElementById("werbung5").style.visibility = "hidden";
	       nr = 3;
	    }	  
	    else
	    if (nr == 3)
	    {
	       document.getElementById("werbung1").style.visibility = "hidden";
	       document.getElementById("werbung2").style.visibility = "hidden";     
	       document.getElementById("werbung3").style.visibility = "visible";
	       document.getElementById("werbung4").style.visibility = "hidden"; 
	       document.getElementById("werbung5").style.visibility = "hidden";
	       nr = 4;
	    }	 
	    else
	    if (nr == 4)
	    {
	       document.getElementById("werbung1").style.visibility = "hidden";
	       document.getElementById("werbung2").style.visibility = "hidden";     
	       document.getElementById("werbung3").style.visibility = "hidden";
	       document.getElementById("werbung4").style.visibility = "visible"; 
	       document.getElementById("werbung5").style.visibility = "hidden";
	       nr = 5;
	    }	 
	    else
	    if (nr == 5)
	    {
	       document.getElementById("werbung1").style.visibility = "hidden";
	       document.getElementById("werbung2").style.visibility = "hidden";     
	       document.getElementById("werbung3").style.visibility = "hidden";
	       document.getElementById("werbung4").style.visibility = "hidden"; 
	       document.getElementById("werbung5").style.visibility = "visible";
	       nr = 1;
	    }	 
	    
	    setTimeout("werbung()",20000);
	}