You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-(2-methoxyphenyl)piperazin-1-yl]-6,7-dihydro-1H-[1,4]dioxino[2,3-f]benzimidazole is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H22N4O3
assistant