For a number, if it is an odd number, multiply it by 1; if it is an even number, subtract 5 from it. This is called one operation, and the number obtained after 8 operations is 37. So what is the starting number?
一个数，如果它是奇数，就把它扩大1倍；如果它是偶数，就把它减去5，这样称作一次操作，经过8次操作后得到的数是37．那么开始的数是多少？
<gadget id="calculator">37 + 5</gadget>
<output>42</output>

<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<gadget id="calculator">21 + 5</gadget>
<output>26</output>

<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<gadget id="calculator">13 + 5</gadget>
<output>18</output>

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

<gadget id="calculator">9 + 5</gadget>
<output>14</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<result>7</result>