You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(3,4-dihydro-2H-chromen-6-yl)-1-[4-(1-methylpyrrole-3-carbonyl)piperazin-1-yl]ethanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25N3O3
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