How many inspection points with serious point level that have no fine?
serious point level refers to point_level = 'Serious '; have no fine refers to fine = 0
SELECT COUNT(DISTINCT T2.point_id) FROM inspection_point AS T1 INNER JOIN violation AS T2 ON T1.point_id = T2.point_id WHERE T1.point_level = 'Serious ' AND T2.fine = 0