How many ships belong to states which has Unitary as government type?
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/governmentType> <http://dbpedia.org/resource/Unitary_state> . ?uri <http://dbpedia.org/ontology/country> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Ship>}
Unitary_state