You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3R,4S)-3-methyl-N-[(3-methylfuran-2-yl)methyl]-1-methylsulfonylpiperidin-4-amine by IUPAC nomenclature, provide its molecular formula.
user
C13H22N2O3S
assistant