#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  vector<vector<int>> G(26);
  vector<bool> H(26, false);
  int N;
  cin >> N;
  for (int i = 0; i < N; i++) {
    string s;
    cin >> s;
    for (int j = 0; j < (int)s.size() - 1; j++) {
      G[s[j] - 'A'].emplace_back(s[j + 1] - 'A');
    }
    for (const auto& e : s) {
      H[e - 'A'] = true;
    }
  }
  int M;
  cin >> M;
  for (int i = 0; i < M; i++) {
    string s;
    cin >> s;
    for (int j = 0; j < (int)s.size() - 1; j++) {
      G[s[j] - 'A'].emplace_back(s[j + 1] - 'A');
    }
  }
  auto topological_sort = [&]() {
    vector<int> in(26, 0);
    for (int i = 0; i < 26; i++) {
      for (const int j : G[i]) {
        in[j]++;
      }
    }
    queue<int> que;
    vector<int> res;
    for (int i = 0; i < 26; i++) {
      if (H[i] && in[i] == 0) {
        que.push(i);
        res.emplace_back(i);
        break;
      }
    }
    while (!que.empty()) {
      const auto u = que.front();
      que.pop();
      for (const auto& 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() == count_if(H.begin(), H.end(), [](auto h) { return h; })) {
    for (const auto& x : res) {
      cout << static_cast<char>(x + 'A');
    }
    cout << '\n';
  } else {
    cout << -1 << '\n';
  }
  return 0;
}