N = int(input())
A = [input() for _ in range(N)]
M = int(input())
B = [input() for _ in range(M)]
from collections import defaultdict
dic = defaultdict(int)
dic2 = defaultdict(int)

S = set()
cnt = 0
for a in A:
    for i in range(len(a)):
        if i > 0:
            dic[a[i-1]] = a[i]
            dic2[a[i]] = a[i-1]
    S.add(a[0])
    cnt += len(a)
for b in B:
    for i in range(len(b)):
        if i > 0:
            dic[b[i-1]] = b[i]
            dic2[b[i]] = b[i-1]
if cnt - len(dic) != 1:
    print(-1)
    exit()

for s in S:
    if s not in dic2:
        st = s
        break
ans = [s]
while s in dic:
    s = dic[s]
    ans.append(s)
print("".join(ans))