How many unique actors or actresses have played themselves (as "Himself" or "Herself") in the dataset?

How many unique actors or actresses have played themselves (as "Himself" or "Herself") in the dataset?: a task in SmolDataEnvs-harbor-eval (Harbor dataset). Files (in /home/user/input, no subfolders): - tmdb 5000 credits.csv - tmdb 5000 movies.csv