A University Management System $($UMS$)$ is designed to manage various tasks within a university, focusing on key interactions with the system. Students can enroll in courses, drop courses, pay fees, and access course details and schedules through the system. Instructors teach courses, manage class schedules, and grade students while also being able to update their profiles and assign coursework. Administrative tasks are handled by staff members, who manage course details and assist with scheduling.

The university organizes departments and courses, with each department headed by an instructor who offers various courses and assigns teaching responsibilities. The system tracks classroom details, including room numbers and capacities, while managing class scheduling. Interactions within the UMS include students enrolling in courses, instructors teaching and grading, and staff managing administrative functions. This structured approach ensures that all university operations are efficiently handled and interconnected.

Based on the previous description, draw a use case diagram of the University Management System.