You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(3aR,4R,6R,6aR)-6-(hydroxymethyl)-2,2-dimethyl-3a,4,6,6a-tetrahydrofuro[3,4-d][1,3]dioxol-4-yl]-5-methyl-2-sulfanylidenepyrimidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H18N2O5S
assistant