You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-ethyl-2-[(3-fluoro-4-hydroxyphenyl)methyl]-3-[2-(4-methylsulfonylphenyl)ethyl]guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H25FIN3O3S
assistant