You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[5-[(4-fluorophenoxy)methyl]-1,3,4-oxadiazol-2-yl]sulfanylmethyl]-8-methylpyrido[1,2-a]pyrimidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H15FN4O3S
assistant