Let $\displaystyle \{s_n\}_{n \in \mathbb{Z}^+}$ be a sequence of real numbers that is bounded below. Prove that $\displaystyle \displaystyle\liminf_{n\rightarrow\infty} s_n = \sup_m \left(\inf_{n > m} s_n\right)$.

I honestly can't even understand the question. I understand that if we let $\displaystyle E$ be the set of numbers $\displaystyle x$ (in the extended real number system) such that $\displaystyle s_{nk} \rightarrow x$ for some subsequence $\displaystyle \{s_{nk}\}$ then $\displaystyle \liminf_{n\rightarrow\infty} s_n = \inf{E}$ refers to the lower limit.

But I'm not really understanding the term on the RHS, much less how to go about proving the equality.

Any hints or suggestions would be greatly appreciated.