ALIBABA 2021 Problem 11

Let $M$ be a compact orientable $2n$ -manifold with boundary, where $n \ge 2$ . Suppose that $H_0(M;\mathbb{Q}) \cong \mathbb{Q}$ and $H_i(M;\mathbb{Q})=0$ for $i>0$ . Prove that the order of $H_{n-1}(\partial M; \mathbb{Z})$ is a square number.