You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[4-(pyridin-3-ylmethylsulfanyl)phenyl]-[4-(1,2,4-triazol-1-yl)piperidin-1-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H21N5OS
assistant