A cylindrical oil barrel has a diameter of 4 decimeters at the bottom and can hold 62.8 liters of oil at most. The distance between the oil surface in the barrel and the mouth of the barrel is 1 decimeter. How many liters of oil are there in the barrel?
一个圆柱形油桶，底面直径4分米，最多可装油62.8升，现桶内油面距桶口l分米，桶内有油多少升？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">62.8 / 12.56</gadget>
<output>5</output>

<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 4</gadget>
<output>50.24</output>

<result>50.24</result>