100 students from Class 3 1 and Class 2 took a photo together. The photographer said: "You have to stand in 5 rows, and the number of people in the last row must be 1 more than the previous row." How many people stand in the first row?
三1班和三2班的100名学生一起拍照，摄影师说："你们要站成5排，后一排人数都要比前一排多1人．"第一排站多少人．
<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<gadget id="calculator">20 - 2</gadget>
<output>18</output>

<result>18</result>