{0, 1}  msd_neg_fib

0 1
0 0 -> 1
0 1 -> 2

1 1
0 0 -> 1
1 0 -> 3
0 1 -> 2

2 0
1 0 -> 1

3 0
1 0 -> 4
1 1 -> 5

4 0
0 0 -> 3

5 1
0 0 -> 1
1 0 -> 3
