Tell me the geographic region that is located in the terrain feature of Oceania and contains the word melanesia in it's name?
SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q82794 . ?sbj wdt:P706 wd:Q538 . ?sbj rdfs:label ?sbj_label . FILTER(CONTAINS(lcase(?sbj_label), 'melanesia')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
geographic region: Q82794 oceania: Q538