#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <stack>
#include <queue>
#include <functional>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <vector>
#include <array>
#include <tuple>
#include <utility>
#include <numeric>
#include <iomanip>
#include <cctype>
#include <cmath>
#include <assert.h>
#include <cstdlib>
#include <list>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using PII = pair<int, int>;
using PLL = pair<ll, ll>;

template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& p) {
    return s << "(" << p.first << ", " << p.second << ")";
}
template<typename T> ostream& operator<<(ostream& s, const vector<T>& v) {
    s << "[";
    for (int i = 0; i < v.size(); i++) s << (i == 0 ? "" : ", ") << v[i];
    s << "]";
    return s;
}

#define ALL(a) (a).begin(), (a).end()

int main() {
    map<char, int> map;
    char revmap[100];
    int id = 0;

    int N;
    cin >> N;
    vector<string> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];

        for (char c : A[i]) {
            map[c] = id;
            revmap[id] = c;

            id++;
        }
    }

    int M;
    cin >> M;
    vector<string> B(M);
    for (int i = 0; i < M; i++) {
        cin >> B[i];
    }

    vector<int> next(map.size(), -1);
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < A[i].size() - 1; j++) {
            int cid = map[A[i][j]],
                nid = map[A[i][j + 1]];
            next[cid] = nid;
        }
    }
    for (int i = 0; i < M; i++) {
        for (int j = 0; j < B[i].size() - 1; j++) {
            int cid = map[B[i][j]],
                nid = map[B[i][j + 1]];
            next[cid] = nid;
        }
    }

    for (int i = 0; i < next.size(); i++) {
        string s = "";
        int id = i;
        while (id >= 0) {
            s.push_back(revmap[id]);
            id = next[id];

        }
        if (s.size() == next.size()) {
            cout << s << endl;
            return 0;
        }
    }
    cout << -1 << endl;

    return 0;
}