. List, for each quarter, the number of courses with fewer than 5 students (but at least one student) enrolled that quarter. The answer should have attributes {qtr, year, num}.

The university registrar database has the following schema: student: sid (string) course: cid (string) prerequisite: cid (string), pre_cid (string) record: sid (string), cid (string), qtr (string), year (integer), grade (integer) Relation student provides the ids of all students enrolled in the university, and course provides all offered courses. Relation prerequisite provides the prerequisites pre_cid for each course cid. Relation record indicates which courses were taken by each student in a given year and quarter (F, W, S), and the grade obtained (for simplicity, grades are provided as integers 4,3,2,1,0, corresponding to A, B, C, D, F). Assume that a class can only be taken