function addToCart(product_id, sum, image)
{
  if (cookies[product_id] != 1)
  {
  products++;
  total_sum += sum;
  document.cookie = "total_sum = "+total_sum
  cookies[product_id] = 1
  image.src = "img/in_cart.gif";
  }
  else if (cookies[product_id] == 1)
  {
  products--;
  total_sum -= sum;
  document.cookie = "total_sum = "+total_sum
  cookies[product_id] = 0;
  image.src = "img/add_cart.gif";
  }

updateCookie();
updateSpan();
}

function updateCookie()
{
    for (i in cookies)
    {
        document.cookie = "product_"+i+"="+cookies[i];
    }
}

function updateSpan()
{
document.getElementById("total_products_in_basket").innerHTML = products;
document.getElementById("total_sum").innerHTML = total_sum;
}