select count(aaa.org_id) as count, aaa.org_id from 
(match (person:/univ_demo/person)-[:person_to_org]->(org:/univ_demo/org) 
return person.id as "person_id", org.id as "org_id") aaa
group by aaa.org_id having count(distinct aaa.person_id)>=20
/**
output()
count(1)
match(org_id,"univ_demo_org:1",count,"1")
**/
;