Description:
This is an unusual problem in an unusual contest, here is the announcement: http://codeforces.com/blog/entry/73543
You are given a directed acyclic graph $$$G$$$ with $$$n$$$ vertices and $$$m$$$ edges. Denote by $$$R(v)$$$ the set of all vertices $$$u$$$ reachable from $$$v$$$ by moving along the edges of $$$G$$$. Find $$$\sum\limits_{v=1}^n |R(v)|^2$$$.
Input Format:
The first line contains two integers $$$n, m$$$ ($$$1 \leq n, m \leq 5 \cdot 10^4$$$) denoting the number of vertices and the number of edges of $$$G$$$.
Each of the next $$$m$$$ lines contains two integers $$$u, v$$$ ($$$1 \leq u \neq v \leq n$$$), denoting the edge from $$$u$$$ to $$$v$$$.
It's guaranteed that the given graph does not contain any cycles.
Output Format:
Print one integer — the answer to the problem.
Note:
None