In the music classroom, the children sit in a square array for class, no matter counting from the front or counting from the back, counting from the left or counting from the right, Xiaohong is the fourth, how many children are there in class?
音乐教室里，小朋友们坐成一个方阵上课，无论从前数，还是从后数从左数从右数，小红都是第4个，一共有多少个小朋友在上课．
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<gadget id="calculator">7 * 7</gadget>
<output>49</output>

<result>49</result>