What is the district of the city with the MAX(number of houses whose instance of is district of the city?
select ?ent where { ?ent wdt:P31 wd:Q21851888 . ?ent wdt:P4080 ?obj . ?ent wdt:P31 wd:Q21851888 } ORDER BY DESC(?obj)LIMIT 5 
district of the city in the czech republic: Q21851888 district of the city in the czech republic: Q21851888