You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 1,4-dioxa-8-azaspiro[4.5]decan-8-yl-[2-[(4-fluorophenyl)methylsulfanyl]pyridin-3-yl]methanone ?
user
C20H21FN2O3S
assistant