You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name (1S)-1-[2-[[(2R,4S)-4-(hydroxymethyl)-2-phenyloxolan-2-yl]methylselanyl]phenyl]propan-1-ol ?
user
C21H26O3Se
assistant