using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = new string[n];
        for (var i = 0; i < n; ++i) s[i] = ReadLine();
        var m = NN;
        var t = new string[m];
        for (var i = 0; i < m; ++i) t[i] = ReadLine();
        var set = new HashSet<char>();
        foreach (var si in s) foreach (var c in si) set.Add(c);
        var list = new List<char>(set);
        list.Sort();
        var dic = new Dictionary<char, int>();
        for (var i = 0; i < list.Count; ++i) dic[list[i]] = i;
        var tree = new HashSet<int>[list.Count];
        for (var i = 0; i < tree.Length; ++i) tree[i] = new HashSet<int>();
        var rev = new int[tree.Length];
        foreach (var si in s)
        {
            for (var i = 1; i < si.Length; ++i)
            {
                tree[dic[si[i - 1]]].Add(dic[si[i]]);
                rev[dic[si[i]]] = 1;
            }
        }
        foreach (var ti in t)
        {
            for (var i = 1; i < ti.Length; ++i)
            {
                tree[dic[ti[i - 1]]].Add(dic[ti[i]]);
                rev[dic[ti[i]]] = 1;
            }
        }
        var zero = 0;
        var zeroi = 0;
        for (var i = 0; i < tree.Length; ++i)
        {
            if (tree[i].Count > 1) zero += 100;
            if (tree[i].Count == 0) ++zero;
            if (rev[i] == 0) zeroi = i;
        }
        if (zero != 1) WriteLine(-1);
        else
        {
            var cur = zeroi;
            var ans = new List<char>();
            while (true)
            {
                ans.Add(list[cur]);
                if (tree[cur].Count == 0) break;
                foreach (var next in tree[cur])
                {
                    cur = next;
                    break;
                }
            }
            WriteLine(string.Concat(ans));
        }
    }
}