100 students stand in a row and count from 1 to 100 from left to right. Those who register with an even number will turn backwards. After reporting, they will count from 1 to 100 from left to right again. Those who register in multiples of 3 will turn backward , and finally count from 1 to 100 from left to right again, and all those who report in multiples of 5 turn backwards. At this time, how many students are facing forward.
100名学生站成一排，从左至右1至100报数，凡报到偶数者均向后转，报完后再次从左至右1至100报数，凡报到3的倍数者均向后转，最后再次从左至右1至100报数，凡报到5的倍数者均向后转，这时面向前的学生共有多少人．
<gadget id="calculator">50 - 17 - 10</gadget>
<output>23</output>

<gadget id="calculator">23 + 3</gadget>
<output>26</output>

<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">16 + 7</gadget>
<output>23</output>

<gadget id="calculator">26 + 23</gadget>
<output>49</output>

<result>49</result>