#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;

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

	vector<bool>used(26);
	vector<vector<char>>link(26);
	for (int i = 0; i < 26; i++)link[i].resize(2);
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < A[i].size(); j++) {
			used[A[i][j] - 'A'] = true;
			if (j > 0)link[A[i][j] - 'A'][0] = A[i][j-1];
			if(j < A[i].size()-1)link[A[i][j] - 'A'][1] = A[i][j + 1];
		}
	}
	for (int i = 0; i < M; i++) {
		for (int j = 0; j < B[i].size(); j++) {
			used[B[i][j] - 'A'] = true;
			if (j > 0)link[B[i][j] - 'A'][0] = B[i][j - 1];
			if (j < B[i].size() - 1)link[B[i][j] - 'A'][1] = B[i][j + 1];
		}
	}

	int alp = 0;
	vector<int>cnt(3);
	for (int i = 0; i < 26; i++) {
		if (used[i]) {
			alp++;
			if (link[i][0] && link[i][1])cnt[2]++;
			else if (link[i][0] == 0 && link[i][1] == 0)cnt[0]++;
			else cnt[1]++;
		}
	}

	if (alp > 1){
		if (cnt[2] == alp - 2 && cnt[1] == 2 && cnt[0] == 0) {

			for (int j = 0; j < 26; j++) {
				if (used[j]) {
					int pos = link[j][0]-'A';
					string s = "";
					s.push_back(char('A' + j));
					while (pos>=0) {
						s.insert(s.begin(), pos + 'A');
						pos = link[pos][0]-'A';
					}
					pos = link[j][1]-'A';
					while (pos>=0) {
						s.push_back(pos + 'A');
						pos = link[pos][1]-'A';
					}

					cout << s << endl;
					break;
				}
			}
		}
		else cout << -1 << endl;
	}
	else {
		cout << A[0] << endl;
	}

    return 0;
}