B"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 . The first line contains two integers n, m ( 1 <= q n, m <= q 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 <= q u neq v <= q n ), denoting the edge from u to v . It's guaranteed that the given graph does not contain any cycles. Print one integer -- the answer to the problem. "...