You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[3-methyl-4-[3-(methylcarbamoyl)phenyl]-1,2-dihydroimidazol-5-yl]pyridine-4-carboxylic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H18N4O3
assistant