#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define lint long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define SZ(v) ((int)v.size())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define POPCNT(n) (__builtin_popcount(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline T LB(vector<T>& v, T a) { return *lower_bound(ALL(v),a); }
template <typename T> inline int LBP(vector<T>& v, T a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline T UB(vector<T>& v, T a) { return *upper_bound(ALL(v),a); }
template <typename T> inline int UBP(vector<T>& v, T a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template <typename T, typename V> typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) { t = v; }
template <typename T, typename V> typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) { for(auto &e : t) fill_v(e,v); }
const lint MOD = 1000000007;
const lint INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;

template <typename T>
struct Compress {
    map<T, int> zip;
    vector<int> unzip;

    Compress() {}

    Compress(vector<T> v)
    {
        sort(v.begin(), v.end());
        v.erase(unique(v.begin(), v.end()), v.end());
        for (int i = 0; i < v.size(); ++i) {
            zip[v[i]] = i;
            unzip.push_back(v[i]);
        }
    }

    int size()
    {
        return unzip.size();
    }
};

struct TopologicalSort {
    vector<vector<int>> g;
    vector<int> indeg, used, _tsort, _front;

    TopologicalSort() {}
    TopologicalSort(int n) : g(n), used(n, 0), indeg(n, 0) {}

    void add_edge(int s, int t)
    {
        g[s].push_back(t);
        indeg[t]++;
    }

    void bfs(int s) {
        queue<int> que;
        que.emplace(s);
        used[s] = 1;
        while (!que.empty()) {
            int v = que.front(); que.pop();
            _tsort.emplace_back(v);
            for (int u : g[v]) {
                indeg[u]--;
                if (!indeg[u] && !used[u]) {
                    used[u] = 1;
                    que.emplace(u);
                }
            }
        }
    }

    vector<int> tsort() {
        int n = g.size();
        for (int i = 0; i < n; ++i) {
            if (!indeg[i] && !used[i]) {
                _front.push_back(i);
                bfs(i);
            }
        }
        return _tsort;
    }

    vector<int> front() {
        return _front;
    }
};

int N, M;
string A[26], B[26];

void _main() {
    vector<char> cs;
    cin >> N;
    REP(i, N) {
        cin >> A[i];
        REP(j, SZ(A[i])) {
            cs.push_back(A[i][j]);
        }
    }
    cin >> M;
    REP(i, M) {
        cin >> B[i];
        REP(j, SZ(B[i])) {
            cs.push_back(B[i][j]);
        }
    }
    Compress c(cs);
    TopologicalSort ts(c.size());
    REP(i, N) {
        REP(j, SZ(A[i]) - 1) {
            ts.add_edge(c.zip[A[i][j]], c.zip[A[i][j + 1]]);
        }
    }
    REP(i, M) {
        REP(j, SZ(B[i]) - 1) {
            ts.add_edge(c.zip[B[i][j]], c.zip[B[i][j + 1]]);
        }
    }
    vector<int> v = ts.tsort();
    if (ts.front().size() != 1) {
        cout << -1 << endl;
        return;
    }
    string ans;
    for (int el : v) {
        ans += c.unzip[el];
    }
    cout << ans << endl;
}

signed main(signed argc, char **argv) {
    if (argc > 1) {
        if (strchr(argv[1], 'i'))
            freopen("input.txt", "r", stdin);
        if (strchr(argv[1], 'o'))
            freopen("output.txt", "w", stdout);
    }
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    _main();
    return 0;
}