Students in a class have their vision tested. The best vision is 2.0, and the worst is 0.2. It is known that there are at least 3 people in the class with the same vision. How many students are there in this class?
一个班的同学进行视力检测，视力最好的是2.0，最差的是0.2，已知全班至少有3个人视力一样，这个班至少有多少名同学？
<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<gadget id="calculator">38 + 1</gadget>
<output>39</output>

<result>39</result>