You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[4-(2-hydroxyethyl)piperazin-1-yl]-4-methyl-7,8-dihydro-6H-quinazolin-5-one by IUPAC nomenclature, provide its molecular formula.
user
C15H22N4O2
assistant