acpc11b.java

import java.io.*;
import java.util.*;

public class acpc11b {
	private static Reader in;
	private static PrintWriter out;
	
	static class Pair implements Comparable <Pair> {
		public int val;
		public boolean type;
		
		public Pair (int val, boolean type) {
			this.val = val;
			this.type = type;
		}
		
		public int compareTo (Pair other) {
			return val - other.val;
		}
	}
	
	public static void main (String [] args) throws IOException {
		in = new Reader ();
		out = new PrintWriter (System.out, true);
		
		int T = in.nextInt();
		while (T-- > 0) {
			PriorityQueue <Pair> pq = new PriorityQueue <Pair> ();
			int N = in.nextInt();
			for (int i = 0; i < N; i++)
				pq.add (new Pair (in.nextInt(), true));
			N = in.nextInt();
			for (int i = 0; i < N; i++)
				pq.add (new Pair (in.nextInt(), false));
			
			int diff = Integer.MAX_VALUE;
			Pair prev = pq.poll();
			while (pq.size() > 0) {
				Pair next = pq.poll();
				if (prev.type ^ next.type) {
					if (next.val - prev.val < diff)
						diff = next.val - prev.val;
				}
				prev = next;
			}
			
			out.println (diff);
		}
		out.close();
		System.exit(0);
	}
	
	static class Reader {
		final private int BUFFER_SIZE = 1 << 16;
		private DataInputStream din;
		private byte [] buffer;
		private int bufferPointer, bytesRead;
		
		public Reader () {
			din = new DataInputStream (System.in);
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}
		
		public Reader (String file_name) throws IOException {
			din = new DataInputStream (new FileInputStream (file_name));
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}
		
		public String readLine () throws IOException {
			byte [] buf = new byte[1024];
			int cnt = 0, c;
			while ((c = read ()) != -1) {
				if (c == '\n')
					break;
				buf[cnt++] = (byte) c;
			}
			return new String (buf, 0, cnt);
		}
		
		public int nextInt () throws IOException {
			int ret = 0;
			byte c = read ();
			while (c <= ' ')
				c = read ();
			boolean neg = (c == '-');
			if (neg)
				c = read ();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read ()) >= '0' && c <= '9');
			if (neg)
				return -ret;
			return ret;
		}
		
		public long nextLong () throws IOException {
			long ret = 0;
			byte c = read ();
			while (c <= ' ')
				c = read ();
			boolean neg = (c == '-');
			if (neg)
				c = read ();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read ()) >= '0' && c <= '9');
			if (neg)
				return -ret;
			return ret;
		}
		
		public double nextDouble () throws IOException {
			double ret = 0, div = 1;
			byte c = read ();
			while (c <= ' ')
				c = read ();
			boolean neg = (c == '-');
			if (neg)
				c = read ();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read ()) >= '0' && c <= '9');
			if (c == '.')
				while ((c = read ()) >= '0' && c <= '9')
					ret += (c - '0') / (div *= 10);
			if (neg)
				return -ret;
			return ret;
		}
		
		private void fillBuffer () throws IOException {
			bytesRead = din.read (buffer, bufferPointer = 0, BUFFER_SIZE);
			if (bytesRead == -1)
				buffer[0] = -1;
		}
		
		private byte read () throws IOException {
			if (bufferPointer == bytesRead)
				fillBuffer ();
			return buffer[bufferPointer++];
		}
		
		public void close () throws IOException {
			if (din == null)
				return;
			din.close ();
		}
	}
}