Contribution #439

Problem: ru/13.4.18

Added 13.2.20 13.4.18

Editor: Aliaksandr Melnichenka ( @astrosander )

Time: November 4, 2023 at 05:57 PM

GitHub commit: bb59f9f665c4da491b9b092b0185aa45a049c95b

+249 -50 lines changed