Contribution #639

Problem: ru/8.4.13

Added 8.4.7 8.4.8 8.4.9 8.4.13 8.4.14

Editor: Aliaksandr Melnichenka ( @astrosander )

Time: November 19, 2023 at 06:59 PM

GitHub commit: 5df87cea8923f276daee08043a19c69c0a1522bf

+252 -50 lines changed