function updateAdCost()
{
	var current = element('camplen').value;
	
	ajax.open( "GET", "/ajax.php?mode=adUpdateCost&len=" + escape( current ), true );
	ajax.send(null);
	
	ajax.onreadystatechange = function ()
	{
		if( ajax.readyState == 4 )
		{
			element('price').value = ajax.responseText;
		}
	}
}