ARC037B

https://gyazo.com/ee65e33af57b50b7a728b664b743d615

Thoughts.

If the number of edges is the number of vertices - 1 for the connected component, then tree

Since the total number of edges is known, is it sufficient to find and calculate the number of connected components? →This is wrong.

There could be a connected component that has multiple extra edges.

Since there are at most 5050 edges, there is plenty of room to find the connected components and then count the number of edges for each connected component.

For each edge, one vertex belongs to

Official Explanation

If there are already visited vertices other than the direction you came from, there is a closed road.

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