N = int(input())
lsA = [input() for i in range(N)]
M = int(input())
lsB = [input() for i in range(M)]
nextls = dict()
Np = 0
for i in range(N):
    s = lsA[i]
    n = len(lsA[i])
    Np += n
    for j in range(n-1):
        nextls[s[j]] = s[j+1]

for i in range(M):
    s = lsB[i]
    m = len(lsB[i])
    for j in range(m-1):
        nextls[s[j]] = s[j+1]

if Np==1:
    print(lsA[0])
    exit()

for key in nextls.keys():
    now = key
    moji = key
    while now in nextls:
        moji += nextls[now]
        now = nextls[now]
    if len(moji) == Np:
        print(moji)
        exit()
print('-1')