You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule ethyl 4-[(4aS,5R)-3-benzyl-9-chloro-3'-methyl-5'-oxospiro[2,4,4a,6-tetrahydro-1H-pyrazino[1,2-a]quinoline-5,4'-pyrazole]-1'-yl]benzoate .
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C31H31ClN4O3
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