How many {start point} are to/by {Denver} ?
Which is the number of star points in Denver?
How many start points are by Denver?
SELECT ( COUNT ( ?o ) AS ?i ) { ?o property:start_point resource:Denver }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1427> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q16554 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P1427 wd:Q16554 }
6