# buy\_buy\_buy

## Description

I got a lot of items to sell so buy buy buy.

Challenge Author: Pranav Goel

## Solution

There was an "auction bot" on Discord.

![](/files/KuvhwXKaDp804xLMGpLz)

It sold different types of items (single, collectable, part and set). The value of a `single` item is static, a `collectable` item increases in value by an arbitrary multiplier when sold, and `parts` can be combined to form a `set` which is worth more than the sum of its parts!

To view the items being sold, we can use `/marketplace`. The goal is to get enough money to buy all three flags (Flag Common, Flag Rare and Flag Ultra Rare).

![](/files/-MgF5k1OL_ybhnvstMI9)

We start off with $10,000. While there are many paths to winning, my strategy ended up being repeatedly buying and selling the Shiny Pokemon Card item.

The first Shiny Pokemon Card was bought for $10,000, but when sold, it made an overall profit of $5000.

![](/files/h5HJzYUp9V9GbsOtrdTa)

![](/files/Kci0cYNfuTqibuNdAciF)

As our balance increases, we could buy and sell more items at a time, increasing the rate at which we earn more profit.

![](/files/E9wBWUHrvLcNTceESFiX)

Repeat this enough times, and we get enough money for all three flags.

![](/files/qYLvehSvqgJcK2dvG4US)

Use `/redeem_flags`, and the bot DMs us the flag!

![](/files/14ZwCXSmspkSZLzwQCom)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ctf.zeyu2001.com/2021/uiuctf-2021/buy_buy_buy.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.
