n个点m条边的图，现把点和边分组，每条边只能和相邻两点之一分在一组，点可以单独一组，问分组方案数。</span></div></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=content><p><font size="4">* Line 1: Two space-separated integers N and M</font></p>
<p><font size="4">&nbsp;* Lines 2..1+