function menu(n, v) {
  var file_name = "menu";
  var path = "img/";
  var separator = "_this";
  var old_src = document.getElementById(file_name + n).src;
  var last_index_of_point = old_src.lastIndexOf(".");
  new_src = (v == 1) ? file_name + n + separator + old_src.substring(last_index_of_point, old_src.length) : file_name + n + old_src.substring(last_index_of_point, old_src.length)
  document.getElementById(file_name + n).src = path + new_src;
}
function link_to(url) {
  window.location.href = "http://www.topmark.ru/" + url;
}