A bag is mixed with 4 black and white glass balls, which are exactly the same in size and shape. If you don't use your eyes to see, you must make sure to touch out two colored glass balls at a time, at least how many glass balls you can get out.
一只袋子里混合放着黑、白玻璃球各4颗，它们的大小、形状完全一样．如果不用眼睛看，要保证一次摸出两种颜色的玻璃球，至少摸出玻璃球多少颗．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>