using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Globalization;
using System.Diagnostics;
using static System.Console;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;
//using System.Numerics;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().Solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    Random rnd = new Random();
    Stopwatch sw = new Stopwatch();
    readonly int[] dd = { 0, 1, 0, -1, 0 };
    readonly int mod = 1000000007;
    readonly string alfa = "abcdefghijklmnopqrstuvwxyz";
    readonly string ALFA = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";


    void Solve()
    {
        int N = cin.Nextint;
        var A = new string[N];
        for (int i = 0; i < N; i++)
        {
            A[i] = cin.Next;
        }
        int M = cin.Nextint;
        var B = new string[M];
        for (int i = 0; i < M; i++)
        {
            B[i] = cin.Next;
        }
        int K = ALFA.Length;
        var used = new bool[K];
        var to = new Pair[K];

        for (int i = 0; i < 26; i++)
        {
            to[i] = new Pair(-2, -2);
        }

        bool flag = true;
        foreach (var v in A)
        {
            for (int i = 0; i < v.Length; i++)
            {
                int x = ALFA.IndexOf(v[i]);
                int l = -1, r = -1;
                if(i > 0)
                {
                    l = ALFA.IndexOf(v[i - 1]);
                }
                if(i < v.Length - 1)
                {
                    r = ALFA.IndexOf(v[i + 1]);
                }
                to[x] = new Pair(l, r);
            }
        }
        foreach (var v in B)
        {
            for (int i = 0; i < v.Length; i++)
            {
                int x = ALFA.IndexOf(v[i]);
                int l = -1, r = -1;
                if (i > 0)
                {
                    l = ALFA.IndexOf(v[i - 1]);
                }
                if (i < v.Length - 1)
                {
                    r = ALFA.IndexOf(v[i + 1]);
                }
                if (to[x].Key >= 0)
                {
                    if (l != -1 && to[x].Key != l) flag = false;
                }
                else
                {
                    to[x] = new Pair(l, to[x].Value);
                }
                if (to[x].Value >= 0)
                {
                    if (r != -1 && to[x].Value != r) flag = false;
                }
                else
                {
                    to[x] = new Pair(to[x].Key, r);
                }
                
            }
        }

        int a = 0, b = 0;
        int ia = -1; int ib = -1;
        for (int i = 0; i < K; i++)
        {
            if (to[i].Key == -1) { a++; ia = i; }
            if(to[i].Value == -1) { b++; ib = i; }
        }

        if (!flag || a != 1 || b != 1)
        {
            WriteLine(-1);
        }
        else
        {
            int u = ia;
            while (true)
            {
                Write(ALFA[u].ToString().ToUpper());
                u = to[u].Value;
                if (u < 0) break;
            }
            WriteLine();
        }
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] Scan { get { return ReadLine().Split(); } }
    public int[] Scanint { get { return Array.ConvertAll(Scan, int.Parse); } }
    public long[] Scanlong { get { return Array.ConvertAll(Scan, long.Parse); } }
    public double[] Scandouble { get { return Array.ConvertAll(Scan, double.Parse); } }
    public string Next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return Next;
        }
    }
    public int Nextint { get { return int.Parse(Next); } }
    public long Nextlong { get { return long.Parse(Next); } }
    public double Nextdouble { get { return double.Parse(Next); } }
}