You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(4-fluorophenyl)-8-[(1-methylimidazol-4-yl)methyl]-1-oxa-4,8-diazaspiro[5.5]undecan-3-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H23FN4O2
assistant