In the physical education class, 30 students stood in a row facing the teacher, and reported the number from left to right according to the teacher's password: 1, 2, 3, ..., 30, and then the teacher asked the students whose numbers were multiples of 2 to move forward. Turn, and then let the students who reported the number that is a multiple of 3 turn back, and finally let the students who reported the number that is a multiple of 5 turn back, how many students are facing the teacher now.
体育课上，30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，…，30，然后，老师让所报的数是2的倍数的同学向后转，接着又让所报的数是3的倍数的同学向后转，最后让所报的数是5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">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">30 - 15</gadget>
<output>15</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 - 5 - 5</gadget>
<output>0</output>

<gadget id="calculator">3 - 3</gadget>
<output>0</output>

<gadget id="calculator">15 + 0 + 0</gadget>
<output>15</output>

<result>15</result>