How many {office held by head of the organisation} are to/by {president} ?
The {president} has how many organisation heads under him?
How many  head of the organisations are under the  {president} ?
SELECT ( COUNT ( ?y ) AS ?w ) { ?y property:office_held_by_head_of_the_organization resource:president }
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/P2388> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q30461 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P2388 wd:Q30461 }
14