5 4 6 5 1 2 3 4 5 1 2 3 4
(1,3)-(4,4)
8 5 12 10 3 4 1 5 6 2 7 8 2 4 11 8 6
(2,6)-(5,11)
4 3 6 5 1 3 4 5 2 4 5
impossible