#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int c = 0;
  vector<int> T(26, -1);
  vector<string> S;
  int N;
  cin >> N;
  for (int i = 0; i < N; i++) {
    string s;
    cin >> s;
    S.emplace_back(s);
    for (const auto& e : s) {
      if (T[e - 'A'] == -1) T[e - 'A'] = c++;
    }
  }
  int M;
  cin >> M;
  for (int i = 0; i < M; i++) {
    string s;
    cin >> s;
    S.emplace_back(s);
    for (const auto& e : s) {
      if (T[e - 'A'] == -1) T[e - 'A'] = c++;
    }
  }
  vector<vector<int>> G(c);
  for (const auto& s : S) {
    for (int i = 0; i < (int)s.size() - 1; i++) {
      G[T[s[i] - 'A']].emplace_back(T[s[i + 1] - 'A']);
    }
  }
  auto topological_sort = [&]() {
    vector<int> in(c, 0);
    for (int i = 0; i < c; i++) {
      for (const int j : G[i]) {
        in[j]++;
      }
    }
    queue<int> que;
    vector<int> res;
    for (int i = 0; i < c; i++) {
      if (in[i] == 0) {
        que.push(i);
        res.emplace_back(i);
        break;
      }
    }
    while (!que.empty()) {
      const auto u = que.front();
      que.pop();
      for (const int v : G[u]) {
        if (--in[v] == 0) {
          que.push(v);
          res.emplace_back(v);
        }
      }
    }
    return res;
  };
  const auto res = topological_sort();
  if ((int)res.size() == c) {
    string s = "";
    for (int r : res) {
      for (int i = 0; i < 26; i++) {
        if (r == T[i]) s += i + 'A';
      }
    }
    cout << s << '\n';
  } else {
    cout << -1 << '\n';
  }
  return 0;
}