You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 9-(4-hydroxy-3,5-dimethoxyphenyl)-5-[3,4,5-trihydroxy-6-[[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]oxan-2-yl]oxy-5a,6,8a,9-tetrahydro-5H-[2]benzofuro[6,5-f][1,3]benzodioxol-8-one by IUPAC nomenclature, provide its molecular formula.
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C33H40O18
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