using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static List<int>[] li;
	static void Main(){
		Sc sc=new Sc();
		int n=26,g=0;
		li=new List<int>[n];
		var h=new int[n];
		for(int i=0;i<n;i++){li[i]=new List<int>();}
		int m=sc.I;
		for(int i=0;i<m;i++){
			var t=sc.S;
			if(m==1&&t.Length==1){
				Console.WriteLine(t);
				return;
			}
			g+=t.Length;
			for(int j = 1;j<t.Length;j++) {li[t[j-1]-'A'].Add(t[j]-'A');}
		}
		m=sc.I;
		for(int i=0;i<m;i++){
			var t=sc.S;
			for(int j = 1;j<t.Length;j++) {li[t[j-1]-'A'].Add(t[j]-'A');}
		}

		Tp tp=new Tp(li,n);

		for(int i = 0;i<n;i++) {
			if(li[tp[i]].Count>0){
				int p=tp[i],z=1;
				while(li[p].Count>0){
					p=li[p][0];
					z++;
				}
				p=tp[i];
				if(z==g){
					Console.Write((char)(p+'A'));
					while(li[p].Count>0){
						p=li[p][0];
						Console.Write((char)(p+'A'));
					}
					Console.WriteLine();
				}
				else {Console.WriteLine(-1);}
				return;
			}
		}
		Console.WriteLine("{0}",-1);
	}
}
public class Tp{
	private bool[] b;
	private int k;
	private List<int>[] li;
	public int[] ar;
	public Tp(List<int>[] li,int n){
		this.li=li;
		b=new bool[n];
		ar=new int[n];
		k=n-1;
		for(int i=n-1;i>=0;i--){if(!b[i]){Fu(i);}}
	}
	public int this[int i]{get{return ar[i];}}
	private void Fu(int a){
		b[a]=true;
		for(int i=0;i<li[a].Count;i++){if(!b[li[a][i]]){Fu(li[a][i]);}}
		ar[k]=a;
		k--;
	}
}

public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}