#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010

/* TopologicalSort */

vector<int> TopologicalSort(vector<vector<int> > G,int n= -1){
  if(n==-1) n=(int)G.size();
  
  int u;
  vector<int> ret,ret2;
  queue<int> que;
  vector<int> indeg(n+1,0);
  
  for(int i=0;i<n;i++){
    for(int j=0;j<G[i].size();j++){
      indeg[G[i][j]]++;
    }
  }
  
  for(int i=0;i<n;i++){
    if(indeg[i]==0){
      que.push(i);
    }
  }
  
  while(!que.empty()){
    u = que.front();
    que.pop();
    
    ret.push_back(u);
    
    for(int i=0;i<G[u].size();i++){
      indeg[G[u][i]]--;
      if(indeg[G[u][i]]==0){
        que.push(G[u][i]);
      }
    }
  }
  
  if(n==(int)ret.size()){
    return ret;
  }else{
    return ret2;
  }
}

bool f[26] = {};

bool check(vector<vector<int> > way, int i, int j, string s){

  way[i].push_back(j);

  auto res = TopologicalSort(way,26);

  if(res.size()){
    return true;
  }
  return false;
}


int main(){
  vector<vector<int> > way(26, vector<int>());

  
  for(int i=0;i<2;i++){
    int n;
    char s[40];

    scanf("%d",&n);

    for(int j=0;j<n;j++){
      scanf("%s",s);

      for(int k=0;s[k]!='\0';k++) f[s[k]-'A'] = true;
      
      for(int k=1;s[k]!='\0';k++){
        way[s[k-1]-'A'].push_back(s[k]-'A');
      }
    }
  }

  auto ans = TopologicalSort(way, 26);

  if(ans.size() == 0){
    puts("-1");
    return 0;
  }
  
  string ans_s = "";
  
  for(int i=0;i<ans.size();i++){
    if(f[ans[i]]) ans_s += 'A' + ans[i];
  }

  for(int i=0;i<ans_s.size();i++){
    for(int j=i+1;j<ans_s.size();j++){
      if(check(way, ans_s[j]-'A', ans_s[i]-'A', ans_s)){
        puts("-1");
        return 0;
      }
    }
  }
  
  cout << ans_s << endl;
  
  return 0;
}