CF915D Almost Acyclic Graph

You are given a [directed graph](https://en.wikipedia.org/wiki/Directed_graph) consisting of $ n $ vertices and $ m $ edges (each edge is directed, so it can be traversed in only one direction). You are allowed to remove at most one edge from it. Can you make this graph [acyclic](https://en.wikipedia.org/wiki/Directed_acyclic_graph) by removing at most one edge from it? A directed graph is called acyclic iff it doesn't contain any cycle (a non-empty path that starts and ends in the same vertex).

N/A

N/A

In the first example you can remove edge , and the graph becomes acyclic. In the second example you have to remove at least two edges (for example,  and ) in order to make the graph acyclic.