You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-(5-chloro-2-methoxyphenyl)-2-[[2-(2,5-difluorophenyl)sulfanylacetyl]-methylamino]acetamide by IUPAC nomenclature, provide its molecular formula.
user
C18H17ClF2N2O3S
assistant