In a certain test, there were only three questions, among which (1/4) students got one wrong question, (1/6) students got two wrong questions, and (1/9) students got three wrong questions. It is known that there are no more than 50 students in the class, how many students have all the correct answers?
某次测验，只有三道题，其中(1/4)的学生错了一道题，(1/6)的学生错了两道题，(1/9)的学生错了三道题．已知全班学生不超过50人，全答对的学生有多少人．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 - (1/4) - (1/6) - (1/9)</gadget>
<output>17/36 = around 0.472222</output>

<gadget id="calculator">36 * (17/36)</gadget>
<output>17</output>

<result>17</result>