You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4-(2,3-dihydroindol-1-yl)-3-(9H-fluoren-9-ylmethoxycarbonylamino)-4-oxobutanoic acid by IUPAC nomenclature, provide its molecular formula.
user
C27H24N2O5
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