import java.io.*;
import java.util.*;


public class Main_yukicoder517 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();

		char[][] a = new char[n][];
		for (int i = 0; i < n; i++) {
			a[i] = sc.next().toCharArray();
		}

		int m = sc.nextInt();

		char[][] b = new char[m][];
		for (int i = 0; i < m; i++) {
			b[i] = sc.next().toCharArray();
		}

		int[] next = new int[26];
		Arrays.fill(next, -2);
		for (char[] s : a) {
			for (int i = 0, size = s.length - 1; i < size; i++) {
				next[s[i] - 'A'] = s[i + 1] - 'A';
			}

			next[s[s.length - 1] - 'A'] = -1;
		}

		for (char[] s : b) {
			for (int i = 0, size = s.length - 1; i < size; i++) {
				next[s[i] - 'A'] = s[i + 1] - 'A';
			}
		}

		Set<Integer> hs = new HashSet<>();
		int cnt = 0;
		for (int i = 0, size = next.length; i < size; i++) {
			if (next[i] == -1) {
				cnt++;
			}

			if (next[i] != -2) {
				hs.add(next[i]);
			}
		}

		if (cnt > 1) {
			pr.println("-1");
			return;
		}

		for (int i = 0, size = next.length; i < size; i++) {
			if (next[i] != -2 && !hs.contains(i)) {
				StringBuilder ret = new StringBuilder();
				int j = i;
				while (j >= 0) {
					ret.append((char)(j + 'A'));
					j = next[j];
				}

				pr.println(ret);
				break;
			}
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}