Convert the uploaded timetable .pdf into a valid .ics calendar file.

Requirements:
- Ignore any class if it only contains a class name and has no schedule information.
- Remove class ID.
- Remove course ID.
- Remove class section identifiers.
- Remove credits.
- Remove lecturer email addresses.
- Remove internal administrative information.
- Everything else should be preserved.
- Create a valid RFC 5545 .ics file.
- Use SUMMARY for the class name.
- Use LOCATION for classroom information.
- Use DESCRIPTION for additional details.
- Do not use new lines \n.
- Separate information using bullet point •.

Example: Giảng viên: Nguyễn Văn A • Phòng: A101 • Lịch học: Thứ 2 07:00-09:30