====== LCA 2 ======

===== 풀이 =====
  * [[ps:LCA]] 쿼리를 처리하는 가장 기본적인 형태의 문제. 풀이는 링크 참고.
  * LCA 쿼리를 처리하는 다양한 방법이 있지만, 실질적인 수행속도는 HLD기반의 O(n+qlogn) 알고리즘이 가장 빨랐다.

===== 코드 =====
<dkpr py>
"""Solution code for "BOJ 11438. LCA 2".

- Problem link: https://www.acmicpc.net/problem/11438
- Solution link: http://www.teferi.net/ps/problems/boj/11438

Tags: [LCA]
"""

import sys
from teflib import tree as ttree

ROOT = 0


def main():
    N = int(sys.stdin.readline())
    tree = [[] for _ in range(N)]
    for _ in range(N - 1):
        u, v = [int(x) for x in sys.stdin.readline().split()]
        tree[u - 1].append(v - 1)
        tree[v - 1].append(u - 1)

    lca = ttree.LowestCommonAncestor(tree, ROOT)
    M = int(sys.stdin.readline())
    for _ in range(M):
        u, v = [int(x) for x in sys.stdin.readline().split()]
        print(lca.lca_node(u - 1, v - 1) + 1)


if __name__ == '__main__':
    main()

</dkpr>
  * Dependency: [[:ps:teflib:tree#LowestCommonAncestor|teflib.tree.LowestCommonAncestor]]

{{tag>BOJ ps:problems:boj:플래티넘_5}}