In the fifth grade, 58 people participated in three extracurricular activities, each of whom participated in at least one of them. 32 people participated in the science and technology group, 27 people participated in the calligraphy group, and 20 people participated in the sports group. Among them, 10 people participated in science and technology and sports. There are 14 people who take part in calligraphy as well as science and technology, and 4 people who take part in both sports and calligraphy. How many people take part in all three?
五年级有58人参加三项课外活动，每人至少参加一项，有32人参加科技组，27人参加书法组，20人参加体育组，其中参加科技又参加体育的有10人，而参加科技又参加书法的有14人，既参加体育又参加书法的有4人，问三项都参加的有几人？
<gadget id="calculator">58 + 10 + 14 + 4</gadget>
<output>86</output>

<gadget id="calculator">32 + 27 + 20</gadget>
<output>79</output>

<gadget id="calculator">86 - 79</gadget>
<output>7</output>

<result>7</result>