You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-N-[1-(2-aminoethyl)pyrazol-3-yl]-2-(3-chloro-4-methylsulfonylphenyl)-3-cyclopentylpropanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H27ClN4O3S
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