The school has organized three interest groups: art, computer, and sports. Xiaoling plans to participate in at least one and at most three. How many different ways does she have to participate in?
学校组织了艺术、电脑、体育3种兴趣小组，小玲准备最少参加1种，最多3种都参加，她一共有多少场不同的参加方式．
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<result>7</result>