You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (5S,18S)-18-hydroxy-4,5,24,24-tetramethyl-25,26-dioxa-7-azaheptacyclo[21.2.1.01,20.04,19.05,16.06,14.08,13]hexacosa-6(14),8,10,12,20-pentaen-22-one by IUPAC nomenclature, provide its molecular formula.
user
C27H31NO4
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