You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named (2S)-2-(5-chloro-1H-indol-3-yl)-2-[4-(2-methoxyphenyl)piperazin-1-yl]acetic acid is given. What is its corresponding molecular formula?
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C21H22ClN3O3
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