There are 6 white rabbits on the grass, 3 black rabbits and 3 gray rabbits, how many colors of rabbits are there on the grass?
草地上有白兔6只，黑兔和灰兔都是3只，草地上有多少种颜色的兔子．
<gadget id="calculator">1 + 1 + 1</gadget>
<output>3</output>

<result>3</result>