Use Stokes' theorem to change ∫∫????∇×????⋅????????????∫∫S∇×F⋅NdS to an equivalent surface integral and evaluate it, where ????=x????+y2????+xyz????F=xi+y2j+xyzk, ????N is the upward unit normal, and ????S is the part of the paraboloid z=4−x2−y2z=4−x2−y2 with z≥0z≥0.