You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-amino-2-[[1-(2-methoxy-5-methylphenyl)tetrazol-5-yl]sulfanylmethyl]-5-methylthieno[2,3-d]pyrimidine-6-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H21N7O3S2
assistant