B. DAGtime limit per test3 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputThis is an unusual problem in an unusual contest, here is the announcement: http://codeforces.com/blog/entry/73543You 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.InputThe 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.OutputPrint one integer — the answer to the problem.ExamplesInput
5 4
1 2
2 3
3 4
4 5
Output
55
Input
12 6
1 2
3 4
5 6
8 7
10 9
12 11
Output
30
Input
7 6
1 2
1 3
2 4
2 5
3 6
3 7
Output
45

5 4
1 2
2 3
3 4
4 5

55 
['constructive algorithms']