For different directors who direct well, how many of them have directed an action film?
direct well means the quality of directing is good, which means d_quality = 4.
SELECT COUNT(DISTINCT T2.directorid) FROM movies2directors AS T2 INNER JOIN directors AS T3 ON T2.directorid = T3.directorid WHERE T2.genre = 'Action' AND T3.d_quality = 4