 the rectangle or on its border.<br />
<br />
How many pairs of friends are there among the given points?</span></div>
<p><span style="font-size: medium">求这样的点对个数：以两点连线为对角线的矩形内不存在其他点（也不能在边界上）</span></p></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">输入格式</h4><div class="ui bottom attached segment font-content"><div style="position: relative; overflow: hidden;"><div class