Please list the IDs of the professors that teaches more than 3 courses.
IDs of the professors refers to taughtBy.p_id and professor = 1; teaches more than 3 courses  refers to count(course_id) > 3
SELECT T1.p_id FROM taughtBy AS T1 INNER JOIN person AS T2 ON T1.p_id = T2.p_id WHERE T2.professor = 1 GROUP BY T1.p_id HAVING COUNT(DISTINCT T1.course_id) > 3
database name:db_id computer_student
course table course Cols: course id dtype integer, course level dtype text, 
person table person Cols: person ID dtype integer, professor dtype integer, student dtype integer, has position dtype text, in phase dtype text, years in program dtype text, 
advisedBy table advisedBy Cols: person id dtype integer, person id dummy dtype integer, 
taughtBy table taughtBy Cols: course ID dtype integer, person ID dtype integer, 
