There are 5 colored flags on each side of the square flower bed, and 1 colored flag on each vertex of the square. How many colorful flags are planted on the four sides of this flower bed.
正方形花坛的每条边上都插了5面彩旗，正方形每个顶点上都有1面彩旗．这个花坛四条边上一共插了多少面彩旗．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<result>16</result>