function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function changeImages() {
  if (document.images && (preloadFlag == true)) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
    }
  }
}

var preloadFlag = false;
function preloadImages() {
  if (document.images) {
    okna_over = newImage("images/okna-over.jpg");
    reshetki_over = newImage("images/reshetki-over.jpg");
    balkony_over = newImage("images/balkony-over.jpg");
    kozyrky_over = newImage("images/kozyrky-over.jpg");
    cond_over = newImage("images/cond-over.jpg");
    remont_over = newImage("images/remont-over.jpg");
    zhaluzi_over = newImage("images/zhaluzi-over.jpg");
    hidro_over = newImage("images/hidro-over.jpg");
    main_over = newImage("images/main-over.jpg");
    preloadFlag = true;
  }
}