You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(2,6-dichlorophenyl)-N-[(S)-(4-fluorophenyl)-(1-methylimidazol-2-yl)methyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H16Cl2FN3O
assistant