n = int(input())
s = [input() for _ in range(n)]
m = int(input())
t = [input() for _ in range(m)]
ds = set(si[0] for si in s)
dt = set(ti[0] for ti in t)
if len(ds&dt)>1:
    print(-1)
else:
    g = {}
    for si in s+t:
        for p,q in zip(si,si[1:]):
            g[p] = q
    ans = []
    v = list(ds&dt)[0]
    while True:
        ans.append(v)
        if v not in g: break
        v = g[v]
    print("".join(ans))