You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[(4-chlorophenyl)methyl]-N-(4-methoxyphenyl)-8-nitro-1,2,4,4a,5,6-hexahydropyrazino[1,2-a]quinoline-5-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H27ClN4O4
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