f(t)=\left\{
\begin{array}{ll}
0, & t<-2,
\vspace{0.5em}\\
1, & -2\leq t<1,
\vspace{0.5em}\\
-2, & 1\leq t<2,
\vspace{0.5em}\\
-1, & 2\leq t<4,
\vspace{0.5em}\\
0, & t\geq 4,
\end{array}
\right.