What is the isotope of lutetium with the highest half-life whose instance of is isotope of lutetium?
select ?ent where { ?ent wdt:P31 wd:Q618200 . ?ent wdt:P2114 ?obj . ?ent wdt:P31 wd:Q618200 } ORDER BY DESC(?obj)LIMIT 5 
isotope of lutetium: Q618200 isotope of lutetium: Q618200