se = set()
n = int(input())
edges = [set() for _ in range(26)]
in_ = [0] * 26
for _ in range(n):
    S = input()
    for s in S:
        se.add(ord(s) - 65)
    for i in range(len(S) - 1):
        p1 = ord(S[i]) - 65
        p2 = ord(S[i + 1]) - 65
        edges[p1].add(p2)
        in_[p2] += 1
n = int(input())
for _ in range(n):
    S = input()
    for i in range(len(S) - 1):
        p1 = ord(S[i]) - 65
        p2 = ord(S[i + 1]) - 65
        edges[p1].add(p2)
        in_[p2] += 1

for i in range(26):
    if in_[i] == 0 and i in se:
        s = i
        break

used = [False] * 26
ans = [chr(65 + s)]
used[s] = True
while 1:
    if len(edges[s]) >= 2:
        print(-1)
        exit()
    elif len(edges[s]) == 0:
        break
    for t in edges[s]:
        break
    if used[t]:
        print(-1)
        exit()
    s = t
    used[s] = True
    ans.append(chr(s + 65))

if len(se) == used.count(True):
    print(*ans, sep="")
else:
    print(-1)