using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Diagnostics;
using Enu = System.Linq.Enumerable;

public class Program
{
    public void Solve()
    {
        int NA = Reader.Int();
        var A = Reader.StringArray(NA);
        int NB = Reader.Int();
        var B = Reader.StringArray(NB);
        var ans = A[0][0] + "";

        for (int prevLen = -1; ans.Length > prevLen; )
        {
            prevLen = ans.Length;
            foreach (var S in new[] { A, B })
                foreach (var s in S)
                    for (int i = 1; i < s.Length; i++)
                    {
                        int pi = ans.IndexOf(s[i - 1]);
                        int ci = ans.IndexOf(s[i]);
                        if (pi >= 0 && ci >= 0 && pi + 1 != ci) { Console.WriteLine(-1); return; }
                        if (pi >= 0 && ci < 0) ans = ans.Insert(pi + 1, s[i] + "");
                        if (ci >= 0 && pi < 0) ans = ans.Insert(ci, s[i - 1] + "");
                    }
        }
        if (ans.Length != string.Concat(A).Length) ans = "-1";

        Console.WriteLine(ans);
    }

    private string Get(string[] A)
    {
        var ans = "";
        foreach (var s in A)
            for (int i = 0; i < s.Length; i++)
            {
                if (ans == "") ans += s[i];
                if (i > 0) ans = ans.Insert(ans.IndexOf(s[i - 1]) + 1, s[i] + "");
            }
        return ans;
    }
}

class Entry { static void Main() { new Program().Solve(); } }
class Reader
{
    static TextReader reader = Console.In;
    static readonly char[] separator = { ' ' };
    static readonly StringSplitOptions op = StringSplitOptions.RemoveEmptyEntries;
    static string[] A = new string[0];
    static int i;
    static void Init() { A = new string[0]; }
    public static void Set(TextReader r) { reader = r; Init(); }
    public static void Set(string file) { reader = new StreamReader(file); Init(); }
    public static bool HasNext() { return CheckNext(); }
    public static string String() { return Next(); }
    public static int Int() { return int.Parse(Next()); }
    public static long Long() { return long.Parse(Next()); }
    public static double Double() { return double.Parse(Next()); }
    public static int[] IntLine() { return Array.ConvertAll(Split(Line()), int.Parse); }
    public static int[] IntArray(int N) { return Range(N, Int); }
    public static int[][] IntTable(int H) { return Range(H, IntLine); }
    public static string[] StringArray(int N) { return Range(N, Next); }
    public static string[][] StringTable(int N) { return Range(N, () => Split(Line())); }
    public static string Line() { return reader.ReadLine().Trim(); }
    public static T[] Range<T>(int N, Func<T> f) { var r = new T[N]; for (int i = 0; i < N; r[i++] = f()) ; return r; }
    static string[] Split(string s) { return s.Split(separator, op); }
    static string Next() { CheckNext(); return A[i++]; }
    static bool CheckNext()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return CheckNext();
        A = Split(line);
        i = 0;
        return true;
    }
}