You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[2-(5-chloro-1H-indol-3-yl)ethylamino]-1-(4-methylphenyl)pyrrolidine-2,5-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H20ClN3O2
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