Through how many cities does the river flowing into Arkansas go?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/mouthMountain> <http://dbpedia.org/resource/Arkansas> . ?x <http://dbpedia.org/ontology/city> ?uri  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/City>}
Arkansas