Semantic tree?

Homework Statement

Show the semantic tree of:

$$\neg ( ( p_0 \rightarrow p_1 ) \rightarrow \neg ( p_1 \rightarrow p_2 ) )$$

Homework Equations

$$\neg ( ( p_0 \rightarrow p_1 ) \rightarrow \neg ( p_1 \rightarrow p_2 ) )$$

The Attempt at a Solution

I cannot understand its purpose. Where should you start?