You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
diethyl (1R,8R,9R,14S)-tetracyclo[6.6.1.02,7.09,14]pentadeca-2,4,6,10,12-pentaene-15,15-dicarboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22O4
assistant