Contribution #1431

Problem: ru/1.2.11

Added 1.2.11, updated 1.2.9,1.2.10,1.2.12

Editor: Aliaksandr Melnichenka ( @astrosander )

Time: June 15, 2024 at 02:11 PM

GitHub commit: bebfcf1373f24705623ffd89897739fdb0a0dabd

+165 -11 lines changed