You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[methyl-[(4-prop-2-enoxyphenyl)methyl]amino]methyl]-3H-thieno[3,2-d]pyrimidin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H19N3O2S
assistant