You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-(3-cyano-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophen-2-yl)-2-(3,4-dimethoxyanilino)propanamide into molecular formula.
user
C21H25N3O3S
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