A originally had a number of books, B borrowed half of them and one more, and the rest of the books C borrowed less than two books, which is exactly half, and the rest of the books D borrowed half and more than three books, and finally left four This book, how many books does A originally have?
A原有若干本书，B借走了一半多1本，剩下的书C借走了差2本就正好是一半，再剩下的书D借走了一半多3本，最后剩下4本书，A原来有书多少本．
<gadget id="calculator">4 + 3</gadget>
<output>7</output>

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

<gadget id="calculator">14 - 2</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">24 + 1</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>