$\mathbb{Z}[\sqrt{-p}]$ fails unique factorization for every odd prime $p$

Let $p$ be an odd prime number and $\mathbb{Z}[\sqrt{-p}]=\{a+b\sqrt{-p}\mid a,b\in\mathbb{Z}\} (\subseteq\mathbf C)$. Then the ring $\mathbb{Z}[\sqrt{-p}]$ is: