You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(1,2-dihydroimidazo[1,2-a]benzimidazol-4-yl)-1-thiophen-2-ylethanone;hydrobromide is the IUPAC name of a molecule. Please give its molecular formula.
user
C15H14BrN3OS
assistant