A total of 49 students from the fourth grade were selected to participate in the opening ceremony of the school sports meeting. They lined up in a square formation. How many people are there in the outermost layer of this phalanx?
四年级共选49位同学参加校运会开幕式，他们排成一个方阵．这个方阵的最外层一共有多少人？
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

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

<result>24</result>