P7056 [NWRRC 2015] Insider’s Information

Ian works for a rating agency that publishes ratings of the best universities. Irene is a journalist who plans to write a scandalous article about the upcoming rating. Using various social engineering techniques (let's not get into more details), Irene received some insider's information from Ian. Specifically, Irene received several triples $(a_{i}, b_{i}, c_{i}),$ meaning that in the upcoming rating, university $b_{i}$ stands between universities $a_{i}$ and $c_{i}.$ That is, either $a_{i}$ comes before $b_{i}$ which comes before $c_{i},$ or the opposite. All triples told by Ian are consistent -- let's say that actual rating satisfies them all. To start working on the first draft of the future article, Irene needs to see at least some approximation to the actual rating. She asked you to find a proposal of a rating in which at least half of the triples known by Irene are satisfied.

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Time limit: 2 s, Memory limit: 256 MB.