A wire 19 cm long can form a square with a side length of 5 cm.
一根长19厘米的铁丝，还差多少厘米就能围成一个边长是5厘米的正方形．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 - 19</gadget>
<output>1</output>

<result>1</result>