You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N'-methyl-N-[2-(2-pyrrolidin-1-yl-1,3-thiazol-4-yl)ethyl]-1-thia-4-azaspiro[5.5]undecane-4-carboximidamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H33N5S2
assistant