You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-(dimethylamino)ethyl]-8-(4-fluorobenzoyl)-2,8-diazaspiro[4.5]decan-1-one;2,2,2-trifluoroacetic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H27F4N3O4
assistant