�你一些点已经被涂色，并</div>
<div>且告诉你是哪一种颜色，问你涂完整棵树有多少种方法?mod 1e9+7。</div>
</div>
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<p></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=content><div>The first line contains two integers N and K (0&le;K&le;N), respectively the number of barns on t