There are only 3 story books and 5 science books in the bookcase. To ensure that you can get two story books at a time, how many books should you take out at least?
书柜里只放着3本故事书和5本科技书，要保证一次拿两本故事书，至少要拿出几本书？
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<result>7</result>