You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (5S)-5-(2,5-difluorophenyl)-2-ethylsulfanyl-1-methyl-6,8-dihydro-5H-pyrido[2,3-d]pyrimidine-4,7-dione .
user
C16H15F2N3O2S
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