You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-ethyl-3-[(1S,2R)-2-methylcyclohexyl]-1-[(4-oxo-3H-quinazolin-2-yl)methyl]thiourea is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H26N4OS
assistant