There are 46 people in class 31, 25 of them participated in the mathematics interest group, 22 participated in the manual interest group, and 18 participated in both interest groups. How many people did not participate in the two interest groups?
三1班有46人，其中25人参加数学兴趣小组，22人参加手工兴趣小组，有18人两个兴趣小组都参加．有多少人两个兴趣小组都没参加．
<gadget id="calculator">22 - 18</gadget>
<output>4</output>

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

<gadget id="calculator">46 - 29</gadget>
<output>17</output>

<result>17</result>