How many {character role} are for {Anna Netrebko} ?
Anna Netrebko has how many roles?
SELECT (COUNT(?obj) AS ?value ) { wd:Q78516 wdt:P453 ?obj }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q78516> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P453> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

Which is the number of the roles of Anna Netrebko?