You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(2,5-dimethylphenoxy)-1-[4-(5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazin-3-yl)piperidin-1-yl]propan-1-one;hydrochloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H30ClN5O2
assistant