There are 3 classes in the fifth grade. In a math competition, at least how many people must win prizes to ensure that there must be 4 students in the same class.
五年级有3个班，在一次数学竞赛中，至少要有多少人获奖，才能保证一定有4名同学是同班的．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<result>10</result>