You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (4aS,8aS)-1-tert-butyl-7-hydroxy-4a,8,8-trimethyl-4-oxo-8a,9-dihydro-5H-benzo[f]indazole-6-carbonitrile .
user
C19H25N3O2
assistant