You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule acetic acid;(3R,5R,8S,9R,10R,13R,14R,16R)-16-bromo-3-hydroxy-10,13-dimethyl-1,2,3,4,5,6,7,8,9,11,12,14,15,16-tetradecahydrocyclopenta[a]phenanthren-17-one into molecular formula.
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C21H33BrO4
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