There are the following numbers: 8, -6.7, 0, -80, -(1/3), -(-4), -|-3|, -(-6**2), which belong to the total number of non-negative integers how many
有下列各数：8，-6.7，0，-80，-(1/3)，-(-4)，-|-3|，-(-6**2)，其中属于非负整数的共有多少个
<gadget id="calculator">-(-4)</gadget>
<output>4</output>

<result>4</result>