There are 50 students in the third class of the fifth grade, 28 students participated in the Chinese competition, 22 students participated in the mathematics competition, and 20 students participated in the English competition. If each person participates in at most two subject competitions, how many people may there be in the class who did not participate in the competition?
五年级三班有50名学生，参加语文竞赛的有28人，参加数学竞赛的有22人，参加英语竞赛的有20人．如果每人最多参加两科竞赛，那么该班未参加竞赛人数最多可能有多少人？
<gadget id="calculator">50 - 35</gadget>
<output>15</output>

<result>15</result>