import itertools
import sys

def main():
    N = int(input())
    A = [input() for i in range(N)]
    M = int(input())
    B = [input() for i in range(M)]

    ans = ''
    for a in A:
        if len(a) > 1:
            break
    else:
        ans = -1
    for b in B:
        if len(b) > 1:
            break
    else:
        ans = -1
    if tuple(sorted(A)) == tuple(sorted(B)):
        ans = -1
    if ans == -1:
        print(-1)
        sys.exit()

    for a in itertools.permutations(A):
        a_ = ''.join(a)
        for b in itertools.permutations(B):
            b_ = ''.join(b)
            if a_ == b_:
                ans = b_
                break

    print(ans)

main()