You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5S,9S)-9-methyl-7-(5-methylfuran-2-carbonyl)-2-pyridin-3-yl-2,7-diazaspiro[4.4]nonan-1-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H21N3O3
assistant