In the sequence -1, (1/2), -(2/2), (1/2), -(1/3), (2/3), -(3/3), (2/3), -(1/3), ..., -(4/4) is the number one.
在数列-1，(1/2)，-(2/2)，(1/2)，-(1/3)，(2/3)，-(3/3)，(2/3)，-(1/3)，…中，-(4/4)是第多少个．
<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">1 + 3 + 5 + 4</gadget>
<output>13</output>

<result>13</result>