You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 4-ethyl-2-(3-ethyl-1,4-dithian-2-yl)-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidine by IUPAC nomenclature, provide its molecular formula.
user
C14H21N3S2
assistant