There are 40 students in the second class of the third grade, 25 of them participated in the art group, 23 participated in the music group, and 19 participated in both groups. How many people did not participate in either group?
三年级二班有40个同学，其中25人参加了美术小组，23人参加了音乐小组，有19人两个小组都参加了．有多少人这两个小组都没参加？
<gadget id="calculator">23 - 19</gadget>
<output>4</output>

<gadget id="calculator">25 + 4</gadget>
<output>29</output>

<gadget id="calculator">40 - 29</gadget>
<output>11</output>

<result>11</result>