using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        var dic = new Dictionary<char, char>();
        var len = 0;
        for (var k = 0; k < 2; k++)
        {
            var n = int.Parse(Console.ReadLine());
            if (n == 1)
            {
                Console.WriteLine(Console.ReadLine());
                return;
            }
            for (var i = 0; i < n; i++)
            {
                var s = Console.ReadLine();
                if (k == 0) len += s.Length;
                for (var j = 0; j < s.Length - 1; j++)
                {
                    if (!dic.ContainsKey(s[j]))
                    {
                        dic.Add(s[j], s[j + 1]);
                    }
                }
            }
        }
        if (dic.Count < len - 1)
        {
            Console.WriteLine(-1);
            return;
        }
        var flg = false;
        var tmp = new List<string>() { "" };
        var next = dic.First().Key;
        for (var i = 0; ; i++)
        {
            if (!dic.ContainsKey(next))
            {
                if (!flg)
                {
                    tmp[tmp.Count - 1] += next;
                    flg = true;
                }
                tmp.Add("");
                if (dic.Count == 0) break;
                next = dic.First().Key;
                continue;
            }
            tmp[tmp.Count - 1] += next;
            char c = dic[next];
            dic.Remove(next);
            next = c;
        }
        var ans = "";
        tmp.Reverse();
        tmp.ForEach((s) => { ans += s; });
        Console.WriteLine(ans);
        return;
    }
}