You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2Z)-2-[(4E)-6-(diethylamino)-3'-oxo-4-[(2Z)-2-(1,3,3-trimethylindol-2-ylidene)ethylidene]spiro[2,3-dihydro-1H-xanthene-9,1'-isoindole]-2'-yl]iminoacetaldehyde by IUPAC nomenclature, provide its molecular formula.
user
C39H40N4O3
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