local n = io.read("*n", "*l")
local s = io.read()
y = 0
for i = 1, n do
  if s:sub(i, i) == "H" then
    print(-1) os.exit()
  end
  if s:sub(i, i) == "Q" then
    y = y + 1
  end
end
z = math.sqrt(y)
if z * z == y then
  print(string.rep(s, z))
elseif (z + 1) * (z + 1) == y then
  print(string.rep(s, z + 1))
else
  print(-1)
end