You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-(1-methylimidazol-2-yl)oxan-4-yl]-3-(5,6,7,8-tetrahydroisoquinolin-3-yl)urea is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H25N5O2
assistant