You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (10aS)-10a-(4-chlorophenyl)-1-(thiadiazole-4-carbonyl)-3,10-dihydro-2H-imidazo[1,2-b]isoquinolin-5-one .
user
C20H15ClN4O2S
assistant