15 students lined up in a horizontal line, counting from the left, Xiao Lin is the 11th; counting from the right, Xiao Gang is the 10th. There are several classmates between Xiaolin and Xiaogang.
15个同学排成一列横队，从左边数起，小林是第11个；从右边数起，小刚是第10个．小林与小刚之间隔几个同学．
<gadget id="calculator">15 - 11</gadget>
<output>4</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">15 - 4 - 5 - 2</gadget>
<output>4</output>

<result>4</result>