You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[(4,5-dimethyl-1,3-oxazol-2-yl)methyl]-1-ethyl-3-[(3-methylthiophen-2-yl)methyl]guanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C15H22N4OS
assistant