Let n be a positive integer and N=n2021. There are 2021 concentric circles centered at O, and N equally-spaced rays are emitted from point O. Among the 2021N intersections of the circles and the rays, some are painted red while the others remain unpainted. It is known that, no matter how one intersection point from each circle is chosen, there is an angle θ such that after a rotation of θ with respect to O, all chosen points are moved to red points. Prove that the minimum number of red points is 2021n2020.[I]Proposed by usjl. combinatoricsconstructionTaiwan