There are 50 students in the fourth grade of Hope Primary School, 26 of them participated in the table tennis competition, 21 of them participated in the basketball competition, and 17 of them did not participate in the two competitions. How many people participated in both games.
希望小学四年级有50名学生，有26人参加乒乓比赛，21人参加篮球比赛，两项比赛都不参加的有17人．两项比赛都参加的有多少人．
<gadget id="calculator">17 - 50</gadget>
<output>-33</output>

<gadget id="calculator">26 + 21 + (-33)</gadget>
<output>14</output>

<result>14</result>