시간 제한메모리 제한제출정답맞힌 사람정답 비율
1 초 128 MB154372838.889%

문제

두더지는 땅에 터널을 파고 생활하는 동물이다. 땅속에 있는 두더지의 집은 방과 터널로 이루어져 있다.

방은 터널로 연결되어 있으며, 한 방에서 다른 방으로 가는 경로는 항상 유일하다. 두 방의 거리는 지나간 터널의 수와 같다.

어느 날, 두더지는 어떤 방과 어떤 방 사이의 거리라 너무 멀다고 생각했다. 두더지는 터널 하나를 막고, 터널 하나를 새로 파서 가장 먼 두 방의 거리를 최소로 만들려고 한다. 이때, 모든 방은 서로 연결되어 있어야 한다.

현재 두더지 집의 상태가 주어졌을 때, 터널 하나를 막고, 하나를 새로 파서 가장 먼 두 방의 거리를 최소로 만드는 프로그램을 작성하시오.

입력

첫째 줄에 방의 개수 N이 주어진다. 방은 1번부터 N번까지 번호 매겨져 있다. (3 ≤ N ≤ 300,000)

다음 N-1개 줄에는 두 방을 연결하는 터널의 정보가 주어진다.

출력

첫째 줄에 재건축을 하고난 이후에 가장 먼 두 집의 거리를 출력한다.

둘째 줄에는 닫을 터널의 정보를 출력한다.

셋째 줄에는 새로 만든 터널의 정보를 출력한다.

정답은 유일하지 않을 수 있다. 이런 경우에는 아무거나 출력하면 된다. 

예제 입력 1

4
1 2
2 3
3 4

예제 출력 1

2
3 4
4 2

예제 입력 2

7
1 3
2 3
2 7
4 3
7 5
3 6

예제 출력 2

3
2 3
7 3
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

출처

Contest > Croatian Open Competition in Informatics > COCI 2008/2009 > Contest #1 6번

  • 문제를 번역한 사람: baekjoon
  • 문제의 오타를 찾은 사람: khsoo01