The oldest student in the school is 13 years old, and the youngest is 6 years old. From the number of students selected, two students of the same age can be found.
学校中年龄最大的同学是13岁，最小的6岁，从多少个同学中挑选，一定可以找到两个同学岁数相同．
<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<result>9</result>