You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[9-ethyl-7-(1H-pyrrol-2-ylmethylideneamino)carbazol-2-yl]-1-(1H-pyrrol-2-yl)methanimine is the IUPAC name of a molecule. Please give its molecular formula.
user
C24H21N5
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