2017 IMO Shortlist G6

Let $n \geq 3$ be an integer. Two regular $n$-gons $\mathcal{A}$ and $\mathcal{B}$ are given in the plane. Prove that the vertices of $\mathcal{A}$ that lie inside $\mathcal{B}$ or on its boundary are consecutive. (That is, prove that there exists a line separating those vertices of $\mathcal{A}$ that lie inside $\mathcal{B}$ or on its boundary from the other vertices of $\mathcal{A}$.) (Czech Republic)

设 $n \geq 3$ 为整数。平面上给出了两个正则 $n$ 边形 $\mathcal{A}$ 和 $\mathcal{B}$。证明 $\mathcal{A}$ 位于 $\mathcal{B}$ 内部或其边界上的顶点是连续的。 (也就是说，证明存在一条线将位于 $\mathcal{B}$ 内部或其边界上的 $\mathcal{A}$ 顶点与 $\mathcal{A}$ 的其他顶点分开。)(捷克共和国)