A number of children form a circle, counting from a classmate. If it goes clockwise, then when reporting to Xiao Ming, he should report "12"; if it goes counterclockwise, then when reporting to Xiao Ming, he should report "8". So how many primary school students are there in this circle?
有若干名小朋友围成一个圆圈，从某个同学开始报数．如果沿顺时针方向，那么报到小明时，他应该报"12"；如果沿逆时针方向，那么报到小明时，他应该报"8"．那么这一圈一共有多少名小学生．
<gadget id="calculator">8 - 2</gadget>
<output>6</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<result>18</result>