You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(5-bromothiophen-2-yl)methyl]-N-ethyl-2-(3-oxopiperazin-1-ium-1-yl)acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C13H19BrN3O2S+
assistant