There are several glass balls in the drawer, and Xiaojun takes out half of them each time and puts one back in. In this way, he takes it five times in total, and there are still 3 glass balls in the drawer. So, how many glass balls are there in the drawer?
抽屉里有若干个玻璃球，小军每次拿出其中的一半再放回一个，这样一共拿了五次，抽屉里还有3个玻璃球，那么，原来抽屉里有多少个玻璃球．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

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

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">2 * 9</gadget>
<output>18</output>

<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<gadget id="calculator">2 * 17</gadget>
<output>34</output>

<result>34</result>