dden;"><h4>样例输入</h4><div class="ui existing segment"><pre style="margin-top:0; margin-bottom:0;"><code class="lang-plain">
			<div class=content><span class=sampledata>5 3<br />
0 1<br />
1 2<br />
2 3<br />
3 2<br />
6 1</span></div></code></pre></div><h4>样例输出</h4><div class="ui existing segment"><pre style="margin-top:0; margin-bottom:0;"><code class="lang-plain">
			<div class=content><span class=sampledata>3</span></div></code></pre></div></div></div></div></div><div class="row"><di