You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(6S,11S)-11-hydroxy-8-methyl-2,8-diazaspiro[5.5]undecan-2-yl]-5,6,7,8-tetrahydroquinoline-3-carbonitrile The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H28N4O
assistant