There are 4 classes in the fifth grade with 217 students. The sum of the number of people in the first two classes is 13 less than that of the last two classes, the first class has 4 more people than the second class, and the fourth class has 5 people less than the third class, so what is the difference between the first class and the fourth class?
五年级一共有4个班，217人．前两个班的人数总和比后两个班少13，一班比二班多4人，四班比三班少5人，那么一班和四班相差多少人．
<gadget id="calculator">217 - 13</gadget>
<output>204</output>

<gadget id="calculator">204 / 2</gadget>
<output>102</output>

<gadget id="calculator">217 - 102</gadget>
<output>115</output>

<gadget id="calculator">115 - 5</gadget>
<output>110</output>

<gadget id="calculator">110 / 2</gadget>
<output>55</output>

<gadget id="calculator">102 + 4</gadget>
<output>106</output>

<gadget id="calculator">106 / 2</gadget>
<output>53</output>

<gadget id="calculator">55 - 53</gadget>
<output>2</output>

<result>2</result>