You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-[[2-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)-4-methylsulfanylbutanoyl]amino]-4-methoxybenzamide into molecular formula.
user
C21H27N3O5S
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