You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl (2S)-3-(3,4-difluorophenyl)-2-[[2-[propan-2-yl(propyl)amino]acetyl]amino]propanoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H26F2N2O3
assistant