Railroad#1979
You are building a toy train network! You have some cities connected by tracks. Each track can only have trains going in ONE direction — either from city to city , or from city to city (but not both ways on the same track).
You want to run as many trains as possible! But here's the rule: you can only run a train between two cities if there's a way to go from one city to the other AND come back, following the directions you chose for the tracks.
Your task is to figure out the maximum number of trains you can run if you choose the best directions for all the tracks.
The first line has two numbers and (1 \leq N \leq 10000, 0 \leq K \leq 100000): the number of cities and the number of tracks. The next lines each have two numbers and (1 \leq A, B \leq N) — the cities connected by a track.
Print one number: the maximum number of trains you can run.
Example 1