You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-(thiophene-2-carbonyl)piperazin-1-yl]-N-(thiophen-2-ylmethyl)pyridine-3-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H20N4O2S2
assistant