What is the full name of the actor who has the highest number of restricted films?
restricted refers to rating = 'R'; highest number of film refers to Max(Count(film_id)); full name refers to first_name, last_name
SELECT T.first_name, T.last_name FROM ( SELECT T1.first_name, T1.last_name, COUNT(T2.film_id) AS num FROM actor AS T1 INNER JOIN film_actor AS T2 ON T1.actor_id = T2.actor_id INNER JOIN film AS T3 ON T2.film_id = T3.film_id WHERE T3.rating = 'R' GROUP BY T1.first_name, T1.last_name ) AS T ORDER BY T.num DESC LIMIT 1