You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2'S,3R)-2'-[3-[(E)-2-[4-(diethylaminomethyl)-3,5-difluorophenyl]ethenyl]-2,3,3a,4,5,6,7,7a-octahydro-1H-indazol-6-yl]-5-methoxyspiro[1H-indole-3,1'-cyclopropane]-2-one by IUPAC nomenclature, provide its molecular formula.
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C31H38F2N4O2
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