You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1R,6R,26S,27R)-6,15-dihydroxy-18-(1-hydroxyethyl)-5,14,26-trimethylspiro[2,10,13,17,24-pentaoxapentacyclo[23.2.1.03,8.08,26.012,14]octacos-4-ene-27,2'-oxirane]-11,23-dione by IUPAC nomenclature, provide its molecular formula.
user
C29H42O11
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