There are 50 students in a refresher class, and there are three refresher courses of A, B, and C. There are 38 people who take the course A, 35 people who take the course B, and 31 people who take the course C. There are 29 students who take both courses A and B, 28 people who take both courses A and C, 26 people who take both courses B and C, and 24 people who take both courses A, B, and C ． Ask the number of people who did not choose the three subjects?
某进修班有50人，开甲、乙、丙三门进修课、选修甲这门课的有38人，选修乙这门课有的35人，选修丙这门课的有31人，兼选甲、乙两门课的有29人，兼选甲、丙两门课的有28人，兼选乙、丙两门课的有26人，甲、乙、丙三科均选的有24人．问三科均未选的人数？
<gadget id="calculator">29 - 24</gadget>
<output>5</output>

<result>5</result>