import itertools

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

    cnt = 0
    for a in itertools.permutations(A):
        for b in itertools.permutations(B):
            a_ = ''.join(a)
            b_ = ''.join(b)
            if a_ == b_:
                ans = a_
                cnt += 1

    if cnt > 1:
        print(-1)
    else:
        print(ans)

main()