In physical education class, 60 students stand in a row facing the teacher, and count from left to right according to the teacher's password: 1, 2, 3, ..., 60, and then the teacher asks the students whose numbers are multiples of 4 to move forward Turn, and then let the students who reported the number that is a multiple of 5 turn back, and finally let the students who reported the number that is a multiple of 6 turn back, how many students are facing the teacher now.
体育课上，60名学生面向老师站成一行，按老师口令，从左到右报数：1，2，3，…，60，然后，老师让所报的数是4的倍数的同学向后转，接着又让所报的数是5的倍数的同学向后转，最后让所报的数是6的倍数的同学向后转，现在面向老师的学生有多少人．
<gadget id="calculator">60 / 4</gadget>
<output>15</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">15 + 6</gadget>
<output>21</output>

<gadget id="calculator">60 - 21</gadget>
<output>39</output>

<gadget id="calculator">5 - 5</gadget>
<output>0</output>

<gadget id="calculator">39 + 0</gadget>
<output>39</output>

<result>39</result>