p = l = document.location.pathname;
l = l.replace(/^(\/[^\/]+\/).*$/, "$1");
if (l == '/advertise/') l = p.replace(/^(\/[^\/]+\/[^\/]+\/).*$/, "$1");
towrite = ('<a href="' + l + '">');

// debug
//alert(towrite);

document.write(towrite);