Six students from the third grade of our school went to participate in sports competitions in the district on behalf of the school. Among them, 4 participated in the long-distance running competition and 4 participated in the long jump competition. How many people participated in both long-distance running and long jump competitions?
我校三年级6名同学代表学校去区里参加体育比赛，其中4人参加长跑比赛，4个人参加跳远比赛，既参加长跑比赛又参加跳远比赛的有多少人．
<gadget id="calculator">4 - 6</gadget>
<output>-2</output>

<gadget id="calculator">4 + (-2)</gadget>
<output>2</output>

<result>2</result>