There are 49 people in a phalanx, so how many people are in the outermost layer of the phalanx?
一个方阵共有49人，那么这个方阵最外层有多少人人．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<gadget id="calculator">28 - 4</gadget>
<output>24</output>

<result>24</result>