题目描述

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给定两个数 n; k ，求出满足条件的树的个数：

</p> <p style="margin-left:18.0pt;text-indent:-18.0pt;mso-list:l0 level1 lfo1;

tab-stops:list 18.0pt" class="MsoNormal">1.<span style="font: 7pt "Times New Roman";">     </span>有 nk 个点，标号为 0; 1,…… nk

2.<span style="font: 7pt "Times New Roman";">     如果i≡j mod N,则I,j间不存在边</span></p>

输入格式

 

一行两个数N,K

输出格式

一行一个数，表示答案Mod 10^9+7

 

2 2

4

数据范围与约定

N,K<=10^9