Contribution #643

Problem: ru/8.4.18

Added 8.4.16 8.4.18

Editor: Aliaksandr Melnichenka ( @astrosander )

Time: November 19, 2023 at 07:30 PM

GitHub commit: ffca8141acc4b700e75ca7a2fb3c27908eba420e

+267 -53 lines changed