local n = io.read("*n", "*l")
local s = io.read()
for i = 1, n do
  if s:sub(i, i) ~= "Q" then
    print(-1) os.exit()
  end
end
z = math.sqrt(n)
if z * z == n then
  print(string.rep("Q", z))
elseif (z + 1) * (z + 1) == n then
  print(string.rep("Q", z + 1))
else
  print(-1)
end