Problem F. Rikka with Graph
时间限制 1000 ms
内存限制 64 MB
As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them:
For an undirected graph $G$ with $n$ nodes and $m$ edges, we can define the distance between $(i,j)$ ($\text{dist}(i,j)$) as the length of the shortest path between $i$ and $j$. The length of a path is equal to the number of the edges on it. Specially, if there are no path between $i$ and $j$, we make $\text{dist}(i,j)$ equal to $n$.
Then, we can define the weight of the graph $G$ ($w_G$) as $\sum_{i=1}^n \sum_{j=1}^n \text{dist}(i,j)$.
Now, Yuta has $n$ nodes, and he wants to choose no more than $m$ pairs of nodes $(i,j)(i \neq j)$ and then link edges between each pair. In this way, he can get an undirected graph $G$ with $n$ nodes and no more than $m$ edges.
Yuta wants to know the minimal value of $w_G$.
It is too difficult for Rikka. Can you help her?
In the sample, Yuta can choose $(1,2),(1,4),(2,4),(2,3),(3,4)$.
输入数据
输出数据
For each testcase, print a single line with a single number -- the answer.
样例输入
样例输出
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