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

public class Hello
{
    public static void Main()
    {
        var d = new Dictionary<char, char>();
        var n = int.Parse(Console.ReadLine().Trim());
        setDic(d, n);
        n = int.Parse(Console.ReadLine().Trim());
        setDic(d, n);
        var res = getAns(d);
        Console.WriteLine(res);
    }
    public static string getAns (Dictionary<char,char> d)
    {
        var c = d.Count(x => x.Value == '?');
        if (c >= 2) return "-1";
        var hs = new HashSet<char>();
        foreach (var x in d) hs.Add(x.Key);
        foreach (var x in d)
                hs.Remove(x.Value);
        var nextchar = hs.First();
        var res = nextchar.ToString();
        while (d[nextchar]!= '?')
        {
            res += d[nextchar];
            nextchar = d[nextchar];
        }
        return res;
    }
    public static void setDic (Dictionary<char,char> d,int n)
    {
        for (int i = 0; i < n; i++)
        {
            var s = Console.ReadLine().Trim();
            var sL = s.Length;
            for (int j = 0; j < s.Length - 1; j++) d[s[j]] = s[j + 1];
            if (!d.ContainsKey(s[sL - 1])) d[s[sL - 1]] = '?';
        }
    }
}