You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1-ethyl-3-[2-(2-fluorophenyl)-2-hydroxyethyl]-2-(2-pyrrolidin-1-yl-2-thiophen-2-ylethyl)guanidine .
user
C21H29FN4OS
assistant