There are 120 students in the sixth grade of a certain school, and the sum of the number of people participating in the sports, literature, and mathematics interest groups is 135. Among them, 15 people have participated in both the sports interest group and the literature interest group. There are 10 people in the mathematics interest group, 8 people in both the literature interest group and the mathematics interest group, and 4 people in all three interest groups. Find the number of people who did not participate in any of the three interest groups.
某校六年级有120名学生，参加体育、文学、数学兴趣小组的人数之和为135，其中，既参加了体育兴趣小组又参加了文学兴趣小组有15人，既参加了体育兴趣小组又参加了数学兴趣小组有10人，既参加了文学兴趣小组又参加了数学兴趣小组有8人，三个兴趣小组都参加的有4人，求三个兴趣小组都没有参加的人数．
<gadget id="calculator">135 - 15 - 10 - 8</gadget>
<output>102</output>

<gadget id="calculator">102 + 4</gadget>
<output>106</output>

<gadget id="calculator">120 - 106</gadget>
<output>14</output>

<result>14</result>