Find the course ID and section ID of the sections that had the minimum enrollment in Fall 2017.

takes student ID course id sec id semester year grade ID name dept_name tot_cred section advisor course course_id title dept_name credits course id sec id semester year building room_number time_slot_id sid department dept name building budget time_slot time_slot_id day start time end_time instructor classroom building room_number capacity prereq course_id prerequid ID name dept_name salary teaches ID course_id sec_id semester year