What is the vallis with the largest diamater and located in the hellas quadrangle?
select ?ent where { ?ent wdt:P31 wd:Q2249285 . ?ent wdt:P2386 ?obj . ?ent wdt:P276 wd:Q3054539 } ORDER BY DESC(?obj)LIMIT 5 
vallis: Q2249285 hellas quadrangle: Q3054539