Circular Buffer Commands

You are required to implement a circular buffer that supports three types of commands: append, get, and remove. The circular buffer has a fixed capacity. When the buffer is full and a new element is appended, the oldest value in the buffer is overwritten.

The commands are defined as follows:

• append X: Append the integer X to the buffer. If the buffer is already full, the oldest value will be replaced.
• get I: Retrieve the value at index I (0-indexed). If the index is invalid (i.e. I is less than 0 or greater than or equal to the current size of the buffer), output Invalid index.
• remove I: Remove the value at index I from the buffer. If the index is invalid, output Invalid index as a result.

The implementation should follow the concept of a circular buffer. In particular, if we denote the fixed capacity as \(C\) and the number of elements currently in the buffer as \(N\), then a valid index must satisfy \(0 \le I < N\).

inputFormat

The input is given via stdin and is formatted as follows:

1. The first line contains two space-separated integers: Q (the number of commands) and capacity (the fixed size of the circular buffer).
2. The next Q lines each contain a command. A command is either: append X, get I, or remove I where X and I are integers.

Note: If the capacity is 0, all get and remove commands should output Invalid index.

outputFormat

Print the results to stdout on a single line, with each result separated by a space. Only the results of a get command or a remove command that returns an error (Invalid index) should be output.

7 3
append 1
append 2
append 3
append 4
get 0
get 2
remove 1

2 4