You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(1,1-dioxothiolan-3-yl)-3-[2-(3-fluorophenyl)-2-morpholin-4-ylethyl]-2-methylguanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H27FN4O3S
assistant