The students of Guangming Primary School lined up in a square formation of 20 people. How many students are standing on the outermost two floors?
光明小学学生排成20人一行的正方形方阵，最外边两层共站多少个学生？
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">80 - 4</gadget>
<output>76</output>

<gadget id="calculator">20 - 2</gadget>
<output>18</output>

<gadget id="calculator">18 * 4</gadget>
<output>72</output>

<gadget id="calculator">72 - 4</gadget>
<output>68</output>

<gadget id="calculator">76 + 68</gadget>
<output>144</output>

<result>144</result>