How many {part of} are to/by {Winter War} ?
In regards to the Winter War, how many were a part of it?
How many are part of Winter War?
SELECT ( COUNT ( ?i ) AS ?x ) { ?i property:part_of resource:Winter_War }
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/P361> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q134949 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P361 wd:Q134949 }
16