题号：NC225907
时间限制：C/C++/Rust/Pascal 4秒，其他语言8秒
空间限制：C/C++/Rust/Pascal 1024 M，其他语言2048 M
64bit IO Format: %lld
时间限制：C/C++/Rust/Pascal 4秒，其他语言8秒
空间限制：C/C++/Rust/Pascal 1024 M，其他语言2048 M
64bit IO Format: %lld
题目描述
Given a integer 
, you are asked to calculate the sum of the diameter of all unrooted labeled trees with nodes labeled from 
to . Here the diameter of a tree is the length of the longest simple path on this tree, and the length of a path is the number of edges along this path.
Since the answer may be too large, you only need to output the result modulo a given prime number
.
Since the answer may be too large, you only need to output the result modulo a given prime number
输入描述:
The input contains two integers, where
输出描述:
Output a single integer, indicating the sum of the diameter of all labeled trees with