You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(3-oxo-4H-1,4-benzoxazin-7-yl)-4-(pyridin-4-ylmethyl)piperazine-1-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H21N5O3
assistant