You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4R)-2-(2-methoxyethyl)-4-(methoxymethyl)-8-(thiophen-2-ylmethyl)-2,8-diazaspiro[4.5]decane is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H30N2O2S
assistant