using Kzrnm.Competitive.IO;
using System;
using System.Buffers.Text;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
namespace TopoSort.Problems
{
    internal partial class Problemyc517
    {
        static void Solve()
        {
            var P = cr.Int();
            var A = cr.Repeat<string>(P);
            var Q = cr.Int();
            var B = cr.Repeat<string>(Q);
            var N = 0;
            var toNums = new Dictionary<char, int>();
            var fromNums = new Dictionary<int, char>();
            foreach (var a in A)
                foreach(var c in a)
                {
                    if (!toNums.ContainsKey(c))
                    {
                        toNums[c] = N;
                        fromNums[N] = c;
                        N++;
                    }
                }
            foreach (var b in B)
                foreach (var c in b)
                {
                    if (!toNums.ContainsKey(c))
                    {
                        toNums[c] = N;
                        fromNums[N] = c;
                        N++;
                    }
                }
            var graph = new HashSet<int>[N];
            for (int i = 0; i < N; i++)
                graph[i] = new HashSet<int>();
            foreach (var a in A)
                for(int i = 0; i < a.Length - 1; i++)
                    graph[toNums[a[i]]].Add(toNums[a[i + 1]]);
            foreach (var b in B)
                for (int i = 0; i < b.Length - 1; i++)
                    graph[toNums[b[i]]].Add(toNums[b[i + 1]]);
            var indegs = new int[N];
            for (int i = 0; i < N; i++)
                foreach (var v in graph[i])
                    indegs[v]++;
            var stk = new Stack<int>();
            for (int i = 0; i < N; i++)
                if (indegs[i] == 0)
                    stk.Push(i);
            if (stk.Count() != 1)
            {
                cw.WriteLine(-1);
                return;
            }
            var dag = new List<int>();
            while(stk.Count() > 0)
            {
                var u = stk.Pop();
                dag.Add(u);
                if (graph[u].Count() > 1)
                {
                    cw.WriteLine(-1);
                    return;
                }
                foreach (var v in graph[u])
                {
                    indegs[v]--;
                    if (indegs[v] == 0)
                        stk.Push(v);
                }
            }
            var ans = "";
            for (int i = 0; i < dag.Count(); i++)
                ans += fromNums[dag[i]];
            cw.WriteLine(ans);
        }
    }
}

#region Dependency resolution
namespace TopoSort.Problems
{
    internal partial class Problemyc517
    {
        static ConsoleReader cr;
        static ConsoleWriter cw;
#if COMPETITIVE
        public Problemyc517(string outputFilePath = null, bool solving = true)
#else
        static void Main(string[] args)
#endif
        {
#if COMPETITIVE
            SourceExpander.Expander.Expand(outputFilePath: outputFilePath);
#endif
            if (cw != null)
                cw.Dispose();
            cr = new ConsoleReader();
            cw = new ConsoleWriter();
#if COMPETITIVE
            if (solving)
#endif
                Solve();
            cw.Dispose();
        }
    }
}
#endregion
#region Expanded by https://github.com/kzrnm/SourceExpander
namespace Kzrnm.Competitive.IO{using static Utf8Parser;using _R=ConsoleReader;using MI=System.Runtime.CompilerServices.MethodImplAttribute;public class ConsoleReader{internal const int BufSize=1<<12;internal readonly Stream input;internal readonly Encoding encoding;internal readonly byte[]buf;internal int pos;internal int len;[MI(256)]public ConsoleReader():this(Console.OpenStandardInput(),Console.InputEncoding,BufSize){}[MI(256)]public ConsoleReader(Stream input,Encoding encoding):this(input,encoding,BufSize){}[MI(256)]public ConsoleReader(Stream input,Encoding encoding,int bufferSize){this.input=input;this.encoding=encoding;buf=new byte[bufferSize];}[MI(256)]private void FillEntireNumber(){if((uint)pos>=(uint)buf.Length)FillNextBuffer();while(buf[pos]<=' ')if( ++pos>=len)FillNextBuffer();if(pos+21>=buf.Length&&buf[buf.Length-1]>' ')FillEntireNumberImpl();}private void FillEntireNumberImpl(){buf.AsSpan(pos,len-pos).CopyTo(buf);len-=pos;pos=0;var numberOfBytes=input.Read(buf,len,buf.Length-len);if(numberOfBytes==0)buf[len++]=10;else if(numberOfBytes+len<buf.Length)buf[buf.Length-1]=10;len+=numberOfBytes;}private void FillNextBuffer(){if((len=input.Read(buf,0,buf.Length))==0){buf[0]=10;len=1;}else if(len<buf.Length)buf[buf.Length-1]=10;pos=0;}[MI(256)]internal byte ReadByte(){if(pos>=len)FillNextBuffer();return buf[pos++];}[MI(256)]public T Read<T>(){if(typeof(T)==typeof(int))return(T)(object)Int();if(typeof(T)==typeof(uint))return(T)(object)UInt();if(typeof(T)==typeof(long))return(T)(object)Long();if(typeof(T)==typeof(ulong))return(T)(object)ULong();if(typeof(T)==typeof(double))return(T)(object)Double();if(typeof(T)==typeof(decimal))return(T)(object)Decimal();if(typeof(T)==typeof(char))return(T)(object)Char();if(typeof(T)==typeof(string))return(T)(object)Ascii();return Throw<T>();}static T Throw<T>()=>throw new NotSupportedException(typeof(T).Name);[MI(256)]public int Int(){FillEntireNumber();TryParse(buf.AsSpan(pos),out int v,out int bc);pos+=bc;return v;}[MI(256)]public uint UInt(){FillEntireNumber();TryParse(buf.AsSpan(pos),out uint v,out int bc);pos+=bc;return v;}[MI(256)]public long Long(){FillEntireNumber();TryParse(buf.AsSpan(pos),out long v,out int bc);pos+=bc;return v;}[MI(256)]public ulong ULong(){FillEntireNumber();TryParse(buf.AsSpan(pos),out ulong v,out int bc);pos+=bc;return v;}[MI(256)]public double Double(){FillEntireNumber();TryParse(buf.AsSpan(pos),out double v,out int bc);pos+=bc;return v;}[MI(256)]public decimal Decimal(){FillEntireNumber();TryParse(buf.AsSpan(pos),out decimal v,out int bc);pos+=bc;return v;}[MI(256)]public string String(){var sb=new List<byte>();;byte b;do b=ReadByte();while(b<=' ');do{sb.Add(b);b=ReadByte();}while(' '<b);return encoding.GetString(sb.ToArray());}[MI(256)]public string Ascii(){var sb=new StringBuilder();byte b;do b=ReadByte();while(b<=' ');do{sb.Append((char)b);b=ReadByte();}while(' '<b);return sb.ToString();}[MI(256)]public string Line(){var sb=new List<byte>();byte b;do b=ReadByte();while(b<=' ');do{sb.Add(b);b=ReadByte();}while(b!='\n'&&b!='\r');return encoding.GetString(sb.ToArray());}[MI(256)]public char Char(){byte b;do b=ReadByte();while(b<=' ');return(char)b;}[MI(256)]public int Int0()=>Int()-1;[MI(256)]public uint UInt0()=>UInt()-1;[MI(256)]public long Long0()=>Long()-1;[MI(256)]public ulong ULong0()=>ULong()-1;[MI(256)]public static implicit operator int(_R cr)=>cr.Int();[MI(256)]public static implicit operator uint(_R cr)=>cr.UInt();[MI(256)]public static implicit operator long(_R cr)=>cr.Long();[MI(256)]public static implicit operator ulong(_R cr)=>cr.ULong();[MI(256)]public static implicit operator double(_R cr)=>cr.Double();[MI(256)]public static implicit operator decimal(_R cr)=>cr.Decimal();[MI(256)]public static implicit operator string(_R cr)=>cr.Ascii();public T[]Repeat<T>(int count){var arr=new T[count];for(int i=0;i<arr.Length;i++)arr[i]=Read<T>();return arr;}}}
namespace Kzrnm.Competitive.IO{using _W=ConsoleWriter;using MI=System.Runtime.CompilerServices.MethodImplAttribute;public sealed partial class ConsoleWriter:IDisposable{private const int BufSize=1<<12;private readonly StreamWriter sw;public StreamWriter StreamWriter=>sw;public ConsoleWriter():this(Console.OpenStandardOutput(),Console.OutputEncoding){}public ConsoleWriter(Stream output,Encoding encoding):this(output,encoding,BufSize){}public ConsoleWriter(Stream output,Encoding encoding,int bufferSize){sw=new StreamWriter(output,encoding,bufferSize);}[MI(256)]public void Flush()=>sw.Flush();[MI(256)]public void Dispose()=>Flush();[MI(256)]public _W Write<T>(T v){sw.Write(v.ToString());return this;}[MI(256)]public _W WriteLine(){sw.WriteLine();return this;}[MI(256)]public _W WriteLine<T>(T v){sw.WriteLine(v.ToString());return this;}[MI(256)]public _W WriteLineJoin<T>(IEnumerable<T>col)=>WriteMany(' ',col);[MI(256)]public _W WriteLineJoin<T1,T2>((T1,T2)tuple)=>WriteLineJoin(tuple.Item1,tuple.Item2);[MI(256)]public _W WriteLineJoin<T1,T2,T3>((T1,T2,T3)tuple)=>WriteLineJoin(tuple.Item1,tuple.Item2,tuple.Item3);[MI(256)]public _W WriteLineJoin<T1,T2,T3,T4>((T1,T2,T3,T4)tuple)=>WriteLineJoin(tuple.Item1,tuple.Item2,tuple.Item3,tuple.Item4);[MI(256)]public _W WriteLineJoin<TTuple>(TTuple tuple)where TTuple:System.Runtime.CompilerServices.ITuple{var col=new object[tuple.Length];for(int i=0;i<col.Length;i++)col[i]=tuple[i];return WriteLineJoin(col);}[MI(256)]public _W WriteLineJoin(params object[]col)=>WriteMany(' ',col);[MI(256)]public _W WriteLineJoin<T1,T2>(T1 v1,T2 v2){sw.Write(v1.ToString());sw.Write(' ');sw.WriteLine(v2.ToString());return this;}[MI(256)]public _W WriteLineJoin<T1,T2,T3>(T1 v1,T2 v2,T3 v3){sw.Write(v1.ToString());sw.Write(' ');sw.Write(v2.ToString());sw.Write(' ');sw.WriteLine(v3.ToString());return this;}[MI(256)]public _W WriteLineJoin<T1,T2,T3,T4>(T1 v1,T2 v2,T3 v3,T4 v4){sw.Write(v1.ToString());sw.Write(' ');sw.Write(v2.ToString());sw.Write(' ');sw.Write(v3.ToString());sw.Write(' ');sw.WriteLine(v4.ToString());return this;}[MI(256)]public _W WriteLines<T>(IEnumerable<T>col)=>WriteMany('\n',col);[MI(256)]public _W WriteGrid<T>(IEnumerable<IEnumerable<T>>cols){foreach(var col in cols)WriteLineJoin(col);return this;}[MI(256)]public _W WriteGrid<TTuple>(IEnumerable<TTuple>tuples)where TTuple:System.Runtime.CompilerServices.ITuple{foreach(var tup in tuples)WriteLineJoin(tup);return this;}[MI(256)]private _W WriteMany<T>(char sep,IEnumerable<T>col){var en=col.GetEnumerator();if(!en.MoveNext())goto End;sw.Write(en.Current.ToString());while(en.MoveNext()){sw.Write(sep);sw.Write(en.Current.ToString());}End:sw.WriteLine();return this;}}}
namespace Kzrnm.Competitive.IO{using MI=System.Runtime.CompilerServices.MethodImplAttribute;public partial class ConsoleWriter{[MI(256)]public ConsoleWriter WriteLine(ReadOnlySpan<char>v){sw.WriteLine(v);return this;}[MI(256)]public ConsoleWriter WriteLineJoin<T>(Span<T>col)=>WriteMany(' ',(ReadOnlySpan<T>)col);[MI(256)]public ConsoleWriter WriteLineJoin<T>(ReadOnlySpan<T>col)=>WriteMany(' ',col);[MI(256)]public ConsoleWriter WriteLines<T>(Span<T>col)=>WriteMany('\n',(ReadOnlySpan<T>)col);[MI(256)]public ConsoleWriter WriteLines<T>(ReadOnlySpan<T>col)=>WriteMany('\n',col);[MI(256)]private ConsoleWriter WriteMany<T>(char sep,ReadOnlySpan<T>col){var en=col.GetEnumerator();if(!en.MoveNext())return this;sw.Write(en.Current.ToString());while(en.MoveNext()){sw.Write(sep);sw.Write(en.Current.ToString());}sw.WriteLine();return this;}}}
namespace SourceExpander{public class Expander{[Conditional("EXP")]public static void Expand(string inputFilePath=null,string outputFilePath=null,bool ignoreAnyError=true){}public static string ExpandString(string inputFilePath=null,bool ignoreAnyError=true){return "";}}}
#endregion Expanded by https://github.com/kzrnm/SourceExpander