You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-(4-methylpiperazin-1-yl)ethyl]-14-oxo-8-oxa-15,16-diazatetracyclo[7.7.1.02,7.013,17]heptadeca-1(16),2(7),3,5,9,11,13(17)-heptaene-4-sulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H23N5O4S
assistant