Given n drinks, find optimum way to spend money if for each drink the price and the expiration date is given

Let’s say we are given $ n$ types of drinks, integer $ m$ representing the budget we have and integer $ d$ representing the cost of delivery when we order some drinks. For each of the $ n$ drinks we are given $ P_i \text{ the price of i-th drink and } E_i – \text{expire date}$ . For example $ (3, 2)$ is representing drink with price $ 3$ for one bottle and the second number means that this drink can be used at most $ 2$ days after we buy it.

We can order as many drinks as we want from each type, but each time we order we are paying $ d$ dollars for delivery. Notice that the delivery doesn’t matter in the day, so we can buy drink with exprite date $ 2$ and used it either today, tomorrow, or the day after tomorrow.

I think that this problem can be solved with greedy strategy, but I’m not able to find anything that can lead to correct result and good time complexity.

Here are some things that I got so far:

We don’t want to buy things that will be expired, so from each drink with price $ P_i$ we will spend at most $ P_i \cdot(E_i + 1)$

Because we may have big budget, it is good to find one way of buying drinks and use it couple times, until we don’t run out of money from the budget.

We will first buy the cheaper drinks and for the more expensive ones we should decide should we make a new order, or buy some drinks from the next type.

I didn’t got anything that lead to correct strategy, so please share some of your ideas.

Which Animal won’t Drink water in its Lifetime?

I have wondered whether any animal can last the longest without water. So I Googled and found that there is an animal called Koala, which don't require water in its lifetime. It quenches its thirst by feeding on eucalyptus leaves, which contains more moisture. Eucalyptus leaves is the fifty percent of the feed for this animal…

See the picture of KOALA below……

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