You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5R)-7-[(4-fluorophenyl)methyl]-2-(1H-imidazol-2-ylmethyl)-2,7-diazaspiro[4.5]decan-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H23FN4O
assistant