You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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3-[(1R)-1-[2-chloro-4-(methylaminomethyl)phenyl]ethoxy]-5-imidazo[1,2-a]pyrazin-3-ylthiophene-2-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20ClN5O2S
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