You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-N-(1,3-benzodioxol-5-ylmethyl)-2-chloro-7-N-ethyl-6-nitroquinazoline-4,7-diamine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H16ClN5O4
assistant