You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (1R,2R,4R)-2,3-dihydroxy-N-methyl-4-[6-(methylamino)-2-(2-thiophen-2-ylethynyl)purin-9-yl]bicyclo[3.1.0]hexane-1-carboxamide into its molecular formula.
user
C20H20N6O3S
assistant