You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-hydroxy-3-[5-[(4-methyl-1,4-diazepan-1-yl)sulfonyl]pyridin-2-yl]-1,3-dihydroindole-2-carbonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H23N5O3S
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