How many cities are around the sea which flows into the Atlantic?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/inflow> <http://dbpedia.org/resource/Atlantic_Ocean> . ?x <http://dbpedia.org/property/cities> ?uri  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/City>}
Atlantic_Ocean