Prove that $ a_1 + a_2 + a_3 + \cdots + a_n \geq n$ if $a_1 a_2 \cdots a_n = 1$

Question

Prove that for any real numbers $a_1, a_2,\ldots, a_n > 0$ $(n \in \mathbb{N}, n \geq 2)$ satisfying $a_1 a_2 \cdots a_n = 1$ we have $ a_1 + a_2 + a_3 + \cdots + a_n \geq n$.