Children's Palace Spring Calligraphy Class, Art Class, Instrumental Music Class Enrollment. Calligraphy class recruited 29 students, art class recruited 28 students, instrumental music class recruited 27 students. Among these students, there are 13 students who apply for calligraphy and fine arts, 12 students who apply for both calligraphy and instrumental music, 11 students who apply for both fine arts and instrumental music, and 5 students who apply for all three subjects. So, how many students are there who only participate in one subject study?
少年宫春季书法班、美术班、器乐班招生．书法班招收了29名学员，美术班招收了28名学员，器乐班招收了27名学员．在这些学员中，既报书法又报美术的有13名，既报书法又报器乐的有12人，既报美术又报器乐的有11名，三个科目都报的有5名．那么，只参加一个科目学习的学员有多少名．
<gadget id="calculator">27 - 13 - 12 - 11</gadget>
<output>-9</output>

<gadget id="calculator">29 + 28 + (-9) + 5</gadget>
<output>53</output>

<gadget id="calculator">53 - 13 - 12 - 11</gadget>
<output>17</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">17 + 10</gadget>
<output>27</output>

<result>27</result>