You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[(2-amino-6-methylpyrimidin-4-yl)amino]-1-(2,3-dihydro-1H-inden-2-yl)pyrrolidin-2-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H21N5O
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