#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int n, m, cnt;
string ans;
vector<string> s1, s2;

int main() {
    // freopen("ring.in", "r", stdin);
    // freopen("ring.out", "w", stdout);
    
    scanf("%d", &n);
    s1.resize(n + 1);
    for (int i = 1; i <= n; ++i) {
        cin >> s1[i];
    }
    scanf("%d", &m);
    s2.resize(m + 1);
    for (int i = 1; i <= m; ++i) {
        cin >> s2[i];
    }

    do {
        do {
            string str1, str2;
            for (int i = 0; i < s1.size(); ++i) {
                str1 += s1[i];
            }
            for (int i = 0; i < s2.size(); ++i) {
                str2 += s2[i];
            }

            bool ok = false;
            for (int i = 0; i < str1.size(); ++i) {
                if (str1[i] != str2[i]) break;
                if (i == str1.size() - 1)    {
                    if (ans != str1 || ans == "") {
                        ++cnt;
                        ok = true;
                    }
                }
            }
            if (cnt > 1) {
                puts("-1");
                return 0;
            }
            if (ok) {
                ans = str1;
            }
        } while (next_permutation(s2.begin(), s2.end()));
    } while (next_permutation(s1.begin(), s1.end()));

    cout << ans << endl;

    return 0;
}