You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2-ethylfuran-3-yl)-(9-imino-9-oxo-9lambda6-thia-1-azaspiro[4.5]decan-1-yl)methanone by IUPAC nomenclature, provide its molecular formula.
user
C15H22N2O3S
assistant