Problem:
LCA: Lowest Common Ancestor

For a rooted tree, find the lowest common ancestor of two nodes u and v.

The given tree consists of n nodes and every node has a unique ID from 0 to n-1 where 0 is the root.

Input

n
k0 c1 c2 ... ck0
k1 c1 c2 ... ck1
:
kn-1 c1 c2 ... ckn-1
q
u1 v1
u2 v2
:
uq vq

The first line of the input includes an integer n, the number of nodes of the tree.

In the next n lines, the information of node i is given. ki is the number of children of node i, and c1, ... cki are node IDs of 1st, ... kth child of node i.

In the next line, the number of queryies q is given. In the next q lines, pairs of u and v are given as the queries.

Output

For each query, print the LCA of u and v in a line.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

Sample Input 1

8
3 1 2 3
2 4 5
0
0
0
2 6 7
0
0
4
4 6
4 7
4 3
5 2

Sample Output 1

1
1
0
0

Solution in C# (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Trace;
using SB = System.Text.StringBuilder;
using static System.Math;
using static System.Numerics.BigInteger;
using static Program.IO.Scanner;

using Number = System.Int64;
#region IO
namespace Program.IO {
	using System.IO;
	using System.Text;
	using System.Globalization;

	public class Printer : StreamWriter {
		public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
		public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
	}
	static public class Scanner {
		public static StreamScanner sc = new StreamScanner(Console.OpenStandardInput());
		public static int ri => sc.Integer();
		public static long rl => sc.Long();
		public static string rs => sc.Scan();
		public static double rd => sc.Double();
	}
	public class StreamScanner {
		public StreamScanner(Stream stream) { str = stream; }

		public readonly Stream str;
		private readonly byte[] buf = new byte[1024];
		private int len, ptr;
		public bool isEof = false;
		public bool IsEndOfStream { get { return isEof; } }

		private byte read() {
			if (isEof) return 0;
			if (ptr >= len) {
				ptr = 0;
				if ((len = str.Read(buf, 0, 1024)) <= 0) {
					isEof = true;
					return 0;
				}
			}
			return buf[ptr++];
		}

		public char Char() {
			byte b = 0;
			do b = read(); while ((b < 33 || 126 < b) && !isEof);
			return (char)b;
		}
		public string Scan() {
			var sb = new StringBuilder();
			for (var b = Char(); b >= 33 && b <= 126; b = (char)read()) sb.Append(b);
			return sb.ToString();
		}
		public string ScanLine() {
			var sb = new StringBuilder();
			for (var b = Char(); b != '\n' && b != 0; b = (char)read()) if (b != '\r') sb.Append(b);
			return sb.ToString();
		}
		public long Long() { return isEof ? long.MinValue : long.Parse(Scan()); }
		public int Integer() { return isEof ? int.MinValue : int.Parse(Scan()); }
		public double Double() { return isEof ? double.NaN : double.Parse(Scan(), CultureInfo.InvariantCulture); }
	}

}

#endregion

#region main
static class Ex {
	static public string AsString(this IEnumerable<char> ie) { return new string(ie.ToArray()); }
	static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") {
		return string.Join(st, ie);
	}

	static public void Main() {
		Console.SetOut(new Program.IO.Printer(Console.OpenStandardOutput()) { AutoFlush = false });
		var solver = new Program.Solver();
		var t = new System.Threading.Thread(solver.Solve, 50000000);
		t.Start();
		t.Join();
		//*/
		//solver.Solve();
		Console.Out.Flush();
	}
}
#endregion

namespace Program {
	public class Solver {
		Random rnd = new Random(0);
		public void Solve() {
			var n = ri;
			var HL = new HLTree(n);
			for (int i = 0; i < n; i++) {
				var k = ri;
				for (int j = 0; j < k; j++) {
					var v = ri;
					HL.AddEdge(i, v);
				}
			}
			HL.Build(0);
			var Q = ri;
			for (int i = 0; i < Q; i++) {
				var u = ri;
				var v = ri;
				var lca = HL.LCA(u, v);
				Console.WriteLine(lca);
			}

		}

		const long INF = 1L << 60;
		static int[] dx = { -1, 0, 1, 0 };
		static int[] dy = { 0, 1, 0, -1 };
		static T[] Enumerate<T>(int n, Func<int, T> f) {
			var a = new T[n]; for (int i = 0; i < a.Length; ++i) a[i] = f(i); return a;
		}
		static T[][] Enumerate<T>(int n, int m, Func<int, int, T> f) {
			return Enumerate(n, x => Enumerate(m, y => f(x, y)));
		}
		static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
	}
}
#region HLTree
public class HLTree {
	int n;
	public List<int>[] G;
	int[] sz, par, d;
	//[L,R)
	int[] L, R, head;
	public HLTree(int N) {
		n = N;
		G = new List<int>[n];
		for (int i = 0; i < n; i++)
			G[i] = new List<int>();
		sz = new int[n];
		par = new int[n];
		d = new int[n];
		head = new int[n];
		L = new int[n];
		R = new int[n];
	}
	public void AddEdge(int u, int v) { G[u].Add(v); G[v].Add(u); }
	public void Build(int root = 0) {
		dfs(root);
		int ptr = 0;
		decomposite(root, ref ptr);

	}
	void dfs(int r) {
		var iter = new int[n];
		var stack = new Stack<int>();
		stack.Push(r); d[r] = 0; par[r] = -1;
		while (stack.Count > 0) {
			var u = stack.Peek();
			var g = G[u];
			if (iter[u] < g.Count) {
				var v = g[iter[u]++];
				if (v == par[u]) continue;
				else {
					d[v] = d[u] + 1;
					par[v] = u;
					stack.Push(v);
				}
			}
			else {
				sz[u]++;
				for (int i = 0; i < g.Count; i++) {
					if (g[i] == par[u]) continue;
					sz[u] += sz[g[i]];
					if (sz[g[i]] > sz[g[0]]) { var tmp = g[0]; g[0] = g[i]; g[i] = tmp; }
				}
				stack.Pop();
			}
		}
	}

	void decomposite(int cur, ref int ptr) {
		var u = cur;
		for (; ; ) {
			L[u] = ptr++;
			head[u] = cur;
			if (G[u].Count > 0 && d[G[u][0]] > d[u]) u = G[u][0];
			else break;
		}
		for (; ; ) {
			var g = G[u];
			for (int p = 1; p < g.Count; p++)
				if (d[g[p]] > d[u]) decomposite(g[p], ref ptr);
			R[u] = ptr;
			if (u == cur) break;
			u = par[u];
		}
	}


	static void Swap<T>(ref T u, ref T v) { var tmp = u; u = v; v = tmp; }
	public int LCA(int u, int v) {
		while (head[u] != head[v]) {
			if (d[head[u]] > d[head[v]]) Swap(ref u, ref v);
			v = par[head[v]];
		}
		if (d[u] > d[v]) Swap(ref u, ref v);
		return u;
	}
}

#endregion