You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-(1,2-dihydroimidazo[1,2-a]benzimidazol-3-yl)-2-(1-methylimidazol-2-yl)sulfanylethanone into its molecular formula.
user
C15H15N5OS
assistant