(List(),List(1,2,3,4,5,6,7,8))
(List(1,2,3,4),List(5,6,7,8))
(List(1,2,3,4,5,6,7,8),List())

(List(),List(8,7,6,5,4,3,2,1))
(List(4,3,2,1),List(8,7,6,5))
(List(8,7,6,5,4,3,2,1),List())

(List(),List(7,2,1,5,4,3,8,6))
(List(2,1,4,3),List(7,5,8,6))
(List(7,2,1,5,4,3,8,6),List())

List(1,2,3,4,5,6,7,8)

(List(),List(1,2,3,4,5,6,7,8))
(List(1,2,3,4),List(5,6,7,8))
(List(1,2,3,4,5,6,7,8),List())

(List(),List(8,7,6,5,4,3,2,1))
(List(4,3,2,1),List(8,7,6,5))
(List(8,7,6,5,4,3,2,1),List())

(List(),List(7,2,1,5,4,3,8,6))
(List(2,1,4,3),List(7,5,8,6))
(List(7,2,1,5,4,3,8,6),List())

List(1,2,3,4,5,6,7,8)

List(List())
List(List(),List(1))
List(List(),List(2),List(1),List(1,2))
List(List(),List(3),List(2),List(2,3),List(1),List(1,3),List(1,2),List(1,2,3))
List(List(),List(4),List(3),List(3,4),List(2),List(2,4),List(2,3),List(2,3,4),List(1),List(1,4),List(1,3),List(1,3,4),List(1,2),List(1,2,4),List(1,2,3),List(1,2,3,4))

queens(1) = List(List((1,1)))
queens(2) = List()
queens(3) = List()
queens(4) = List(List((4,3),(3,1),(2,4),(1,2)),List((4,2),(3,4),(2,1),(1,3)))

queens(1) = List(List(1))
queens(2) = List()
queens(3) = List()
queens(4) = List(List(3,1,4,2),List(2,4,1,3))