#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define rep(i,b) FOR(i,0,b)
#define INF 1e9

using ll = long long;
const ll mod = LLONG_MAX;

typedef pair<int,int> P;

int n,m,len;
string a[30],b[30];
int nextt[30];
int main(){
  cin>>n;
  rep(i,n){
    cin>>a[i];
    len+=a[i].size();
  }
  cin>>m;
  rep(i,m){
    cin>>b[i];
  }

  rep(i,30)nextt[i]=-1;

  //cout<<a[0][1]-'A'<<endl;
   rep(i,n){
     for(int j=0;j<a[i].size()-1;j++){
       nextt[a[i][j]-'A']=a[i][j+1]-'A';
     }
   }
   rep(i,m){
     for(int j=0;j<b[i].size()-1;j++){
       nextt[b[i][j]-'A']=b[i][j+1]-'A';
     }
   }

   if(n==m&& n==1){
     cout<<a[0]<<endl;
     return 0;
   }
   int temp=0;
   string ans="";
   string real_ans="";


   for(int k=0;k<26;k++){
     ans="";
     ans+='A'+k;
       for(int i=0;i<30;i++){
         if(nextt[ans[i]-'A']==-1)break;
         ans+=(nextt[ans[i]-'A']+'A');
      }
      if(ans.size()>real_ans.size()){
        real_ans=ans;
      }
  }
   if(real_ans.size()<len){
     cout<<-1<<endl;
     return 0;
   }
  cout<<real_ans<<endl;





}