From Wiktionary, the free dictionary
пусты́ни • (pustýni) f inan or f inan pl
- inflection of пусты́ня (pustýnja):
- genitive singular
- nominative/accusative plural
пу́стыни • (pústyni) f inan or f inan pl
- inflection of пу́стынь (pústynʹ):
- genitive/dative/prepositional singular
- nominative/accusative plural