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 6-(4-chloro-3-nitrophenyl)-4-ethyl-8-methyl-2,3,4,6-tetrahydropyrimido[2,1-b][1,3]thiazine-7-carboxylic acid .
user
C17H18ClN3O4S
assistant