You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-imino-7-methyl-3-(phenylmethoxymethyl)-2,3,4,5-tetrahydropyrrolo[3,4-f]thiazepine-6-carbaldehyde The above is the IUPAC name of a molecule. Write its molecular formula.
user
C17H21N3O2S
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