You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-phenyl-N-(2-propan-2-yl-5,6,7,8-tetrahydro-[1,2,4]triazolo[1,5-a]pyridin-6-yl)-1,3-thiazol-2-amine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H21N5S
assistant