100 students stand in a row. Counting from front to back, all students standing in positions that are multiples of 3 face the front, and the rest of the students face the rear. When two adjacent students face each other, they will shake hands once, and then turn around at the same time. How many times have you shaken hands when no one is face to face?
100名学生站成一列．从前到后数，凡是站在3的倍数位置的学生都面向前方，其余学生都面向后方．当相邻两个学生面对面时，他们就会握一次手，然后同时转身．当不再有人面对面时，一共握过了多少次手．
<gadget id="calculator">66 + 2</gadget>
<output>68</output>

<gadget id="calculator">66 / 2</gadget>
<output>33</output>

<gadget id="calculator">33 / 2</gadget>
<output>33/2 = around 16.5</output>

<gadget id="calculator">68 * (33/2)</gadget>
<output>1_122</output>

<result>1_122</result>