# Peaceable Queens

Challenging

This task is adapted from following video with Neil Sloane (founder of the On-Line Encyclopedia of Integer Sequences), that you should watch first to learn, how this excellent puzzle works.

You are given a chessboard of custom dimension: size * size. Your goal is to put there as many ♕ and ♛ as possible with these rules of placement:

• only equal numbers of Queens are allowed;
• ♕ must not attack ♛ and visa verse (but they may be under "attack" of the same color Queens).

Your function should return the maximum number of opposite Queens pairs, you could put on the given chessboard according to the restrictions.

Input: Size of the chessboard as integer.

Output: Maximum number of opposite Queens pairs as integer.

Examples:

```assert peaceable_queens(1) == 0
assert peaceable_queens(2) == 0
assert peaceable_queens(3) == 1
assert peaceable_queens(4) == 2
```
Settings
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CheckiO Extensions

CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.

In order to install CheckiO client you'll need installed Python (version at least 3.8)

Install CheckiO Client first:

`pip3 install checkio_client`

`checkio --domain=py config --key=`

Sync solutions into your local folder

`checkio sync`

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`checkio serv -d`

Alternatevly, you can install Chrome extension or FF addon

`checkio install-plugin`
`checkio install-plugin --ff`
`checkio install-plugin --chromium`

Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.

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