Повернення до головоломок

Скільки королев (ферзів) потрібно, щоб атакувати всю шахівницю?

Відповідь: П'ять. наприклад:

  1 2 3 4 5 6 7 8
  ___ ___ ___ ___ ___ ___ ___ ___
 h |  |  |  |  |  |  |  |  |
  --- --- --- --- --- --- --- ---
 g |  |  |  |  Q |  |  |  |  |
  --- --- --- --- --- --- --- ---
 f |  |  |  |  Q |  |  |  |  |
  --- --- --- --- --- --- --- ---
 e |  |  |  |  Q |  |  |  |  |
  --- --- --- --- --- --- --- ---
 d |  |  |  |  Q |  |  |  |  |
  --- --- --- --- --- --- --- ---
 c |  |  |  |  |  |  |  |  |
  --- --- --- --- --- --- --- ---
 b |  |  |  |  |  |  |  |  |
  --- --- --- --- --- --- --- ---
 a |  |  |  |  Q |  |  |  |  |
  --- --- --- --- --- --- --- ---