[(2, 1), (1, 2), (1, 3), (1, 4), (1, 5), (2, 6), (2, 7)]
[(1, 2), (1, 3), (1, 4), (1, 5), (2, 1), (2, 6), (2, 7)]
(1, 1, 1, 1, 2, 2, 2) (2, 3, 4, 5, 1, 6, 7)
1 ,  remaining: 5
3 4
3 5
3 6
1 ,  remaining: 5
3 4
3 5
3 6
1 ,  remaining: 5
3 4
3 5
3 6
1 ,  remaining: 5
4 5
4 6
2 ,  remaining: 4
5 6
2 2 2