<sub>标签

<p>The coordinate of the
    <var>i</var>
    th point is (
    <var>x
        <sub>
            <var>i</var>
        </sub>
    </var>, 
    <var>y
        <sub>
            <var>i</var>
        </sub>
    </var>)
    . For example, the 10th point has coordinate (
    <var>x
        <sub>10</sub>
    </var>, 
    <var>y
        <sub>10</sub>
    </var>).
</p>