def bye
  p -1
  exit
end

gets

li = gets.chomp
abort unless li=~/^[A-Za-z]+$/
if li=~/H/
  bye
else
  m = li.count('Q')
  bye if m == 0
  q = Math::sqrt(m).to_i
  bye if (q**2 != m)
  n = li.size
  bye if (n/q*q != n)
  k = n/q
  pat = li[0...k]
  0.step(n-1, k) do |i|
    bye if pat != li[i...(k+i)]
  end
  
  puts pat
end