import itertools

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

    if tuple(sorted(A)) == tuple(sorted(B)):
        ans = -1
    else:
        cnt = 0
        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()