update REPORT.md

update README.md

Запрос на слияние 'practice10-when-holidays' (#2) из practice10-when-holidays в master

delete tasks/task_variants.md

update README.md

create demo/chat.md

create README.md

delete tasks/task_variants.md

update README.md

create demo/chat.md

create README.md

delete demo/delete.md

upload files

create demo/delete.md

delete demo/delete.md

create demo/delete.md

update dev/solution.cs

delete dev/Delete.md

upload files

create dev/Delete.md