In the physical education class, the teacher arranged a game of "cat and mouse" to form a circle with a circumference of 18 meters. Every two adjacent students are separated by 1 meter. How many students are needed to form this circle?
体育课上老师安排了"猫捉老鼠"的游戏，围成一个周长18米的圆，每相邻两名同学间隔1米，围成这个圆需要多少名同学．
<gadget id="calculator">18 / 1</gadget>
<output>18</output>

<result>18</result>