How many {performer} are for {The Song of the Volga Boatmen} ?
The Song of the Volga Boatmen is performed by how many people?
How many people perform The Song of the Volga Boatmen?
SELECT ( COUNT ( ?m ) AS ?s ) { resource:The_Song_of_the_Volga_Boatmen property:performer ?m }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1555383> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P175> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q1555383 wdt:P175 ?obj }
6