How many {interested in} are for {Daniel Dennett} ?
Daniel Dennett is interested in by how many people?
How many are interested in Daniel Dennett?
SELECT ( COUNT ( ?r ) AS ?y ) { resource:Daniel_Dennett property:interested_in ?r }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q215263> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2650> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q215263 wdt:P2650 ?obj }
4