M: Line i+1 describes the ith trail. Each line contains two space-separated integers u_i and v_i (1 &lt;= u_i, v_i &lt;= N, u_i != v_i) describing the pair of farms connected by the trail.&nbsp;&nbsp;Note that there can be two trails between the same pair of farms. </font></p></div></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">输出格式</h4><div class="ui bottom attached segment font-content"><div style="position: relative; overflow: hidden;"><div c