How many islands belong to archipelagos located in the pacific?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/location> <http://dbpedia.org/resource/Pacific_Ocean> . ?uri <http://dbpedia.org/property/archipelago> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Island>}
Pacific_Ocean