You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 3-benzyl-N-(2,5-difluorophenyl)-5-methyl-4-oxothieno[2,3-d]pyrimidine-6-carboxamide .
user
C21H15F2N3O2S
assistant