You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-(2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazin-7-yl)-N-[4-(4-ethylpiperazin-1-yl)phenyl]imidazo[1,2-a]pyrazin-8-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C25H28N8O
assistant