#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
N = int(readline())
A = [readline().decode().rstrip() for _ in range(N)]
M = int(readline())
B = [readline().decode().rstrip() for _ in range(M)]


# %%
E = dict()
V = set()
for word in A + B:
    V |= set(word)
    for x, y in zip(word, word[1:]):
        E[x] = y

# %%
def solve(V, E):
    start = V - set(E.values())
    if len(start) != 1:
        return None
    x = start.pop()
    chain = [x]
    while True:
        if x not in E:
            break
        x = E[x]
        chain.append(x)
    if len(chain) < len(V):
        return None
    return ''.join(chain)

# %%
S = solve(V,E)
if not S:
    print(-1)
else:
    print(S)


# %%