You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[3-[(2-amino-5-chloropyrimidin-4-yl)amino]-4-methylphenyl]-2-(1,3-thiazol-2-yl)but-3-yn-2-ol The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H16ClN5OS
assistant