January through August are reported in the table below.

$\begin{array}{cc}\text{M}\text{o}\text{n}\text{t}\text{h}& \text{S}\text{a}\text{l}\text{e}\text{s}\\ \text{J}\text{a}\text{n}\text{u}\text{a}\text{r}\text{y}& 12\\ \text{F}\text{e}\text{b}\text{r}\text{u}\text{a}\text{r}\text{y}& 12\\ \text{M}\text{a}\text{r}\text{c}\text{h}& 22\\ \text{A}\text{p}\text{r}\text{i}\text{l}& 27\\ \text{M}\text{a}\text{y}& 15\\ \text{J}\text{u}\text{n}\text{e}& 18\\ \text{J}\text{u}\text{l}\text{y}& 31\\ \text{A}\text{u}\text{g}\text{u}\text{s}\text{t}& 39\end{array}$

Computed forecast values are not rounded.

Compute the mean absolute deviation $($MAD$)$ for four$-$period moving average forecasts.

$|$ Round to a whole number.