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 1-ethyl-5-[(2-pyrazin-2-yl-1,3-thiazol-4-yl)methylamino]-4,5,6,7-tetrahydroindazole-3-carboxylic acid .
user
C18H20N6O2S
assistant