You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(3,4-dihydro-2H-1,5-benzodioxepin-7-yl)-3-ethyl-2-[(1-propylpyrrolidin-3-yl)methyl]guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H33IN4O2
assistant