You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule 1-[2-[(2E)-2-(2,7a-dihydro-1H-indol-3-ylmethylidene)hydrazinyl]-4-methyl-1,3-thiazol-5-yl]ethanone ?
user
C15H16N4OS
assistant