local n = io.read("*n", "*l")
local t = {}
for i = 1, 26 do t[i] = 0 end
local s1 = {}
for i = 1, n do
  local s = io.read()
  s1[i] = s
  for j = 1, #s do
    local v = s:byte(j) - 64
    t[v] = t[v] + 1
  end
end
local m = io.read("*n", "*l")
for i = 1, m do
  local s = io.read()
  s1[i + n] = s
  for j = 1, #s do
    local v = s:byte(j) - 64
    t[v] = t[v] + 1
  end
end
local w = {}
for i = 1, 26 do
  if t[i] == 1 then print(-1) os.exit() end
  if t[i] == 2 then
    table.insert(w, i)
    t[i] = #w
  end
end
local parent = {}
local left, right = {}, {}
for i = 1, #w do
  parent[i] = i
  left[i], right[i] = false, false
end

local function uf_findroot(idx)
  local idx_update = idx
  while parent[idx] ~= idx do
    idx = parent[idx]
  end
  while parent[idx_update] ~= idx do
    parent[idx_update], idx_update = idx, parent[idx_update]
  end
  return idx
end

for i = 1, n + m do
  local si = s1[i]
  for j = 1, #si - 1 do
    local z1, z2 = t[si:byte(j) - 64], t[si:byte(j + 1) - 64]
    local r1, r2 = uf_findroot(z1), uf_findroot(z2)
    if r1 ~= r2 then
      parent[r2], parent[z2] = r1, r1
    end
    if right[z1] and right[z1] ~= z2 then
      print(-1) os.exit()
    end
    if left[z2] and left[z2] ~= z1 then
      print(-1) os.exit()
    end
    left[z2] = z1
    right[z1] = z2
  end
end
local r = uf_findroot(1)
for i = 2, #w do
  if r ~= uf_findroot(i) then
    print(-1) os.exit()
  end
end
while r do
  io.write(string.char(64 + w[r]))
  r = right[r]
end
io.write("\n")