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-[4-bromo-1-[(2-chlorophenyl)methyl]pyrazol-3-yl]-3-[1-(1-ethylpyrazol-3-yl)ethyl]thiourea .
user
C18H20BrClN6S
assistant