However, when scheduling the delivery, you noticed that the total supply of 2022-12-31 was not enough, so you contacted an engine oil retailer to provide extra Green Oil and asked the retailer to deliver the difference to each station directly. The retailer charges $ 5 per liter for shipping in general. (Here, you are the transportation manager, and you only consider the shipping cost, including those from the retailer to each station). There are several special requirements that you must satisfy: Station 3 only needs standard oil and premium oil and the amount of premium should be at least twice the standard oil. Station 4 requires at least 1000 liters of standard oil and 1000 liters of premium