Mix 10 small flags of red, white and blue colors together. If you are asked to close your eyes and take it, how many small flags should you take at least each time to ensure that there must be two small flags of the same color.
把红白蓝三种颜色的小旗各10面混在一起．如果让你闭上眼睛拿，每次至少拿多少面小旗才能保证一定有两面小旗是同色的．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>