You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
8-bromo-3-[4-[6-(trifluoromethyl)-1H-benzimidazol-2-yl]phenyl]-1,8a-dihydro-[1,2,4]triazolo[1,5-a]pyridin-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H13BrF3N5O
assistant