There is a fish whose head is 4 centimeters long. The length of the fish body is the sum of the lengths of the head and tail, and the tail is the sum of half the head and half the body. Please calculate the total length of this fish in centimeters.
有一条鱼，鱼头长4厘米，鱼身长是鱼头、鱼尾长的和，而鱼尾是半头、半身之和，请你算一算，这条鱼全长是多少厘米．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">4 + 8</gadget>
<output>12</output>

<gadget id="calculator">4 + 12 + 8</gadget>
<output>24</output>

<result>24</result>