You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2,4,6-tris[2-(10-ethylphenothiazin-3-yl)ethenyl]-5-isocyanobenzene-1,3-dicarbonitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C57H42N6S3
assistant