You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-tert-butyl-2-azaspiro[3.3]heptane;4-tert-butyl-1,4-thiazinane 1,1-dioxide;methane is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H40N2O2S
assistant