There are 5 red and 5 blue ping-pong balls in a box with the same shape and texture, at least how many ping-pong balls can be taken out to ensure that 2 ping-pong balls of different colors can be taken out.
一个盒子里有形状、质地相同的红，蓝乒乓球各5个，至少拿出多少个，才能保证取出2个颜色不同的乒乓球．
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>