Count the number of artists who trained at the San Francisco Art Institute?
SELECT DISTINCT COUNT(?uri) WHERE {?uri <http://dbpedia.org/property/training> <http://dbpedia.org/resource/San_Francisco_Art_Institute>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Artist>}
San_Francisco_Art_Institute