U | a | b | c | e | d |
e1 | 0 | 1 | 0 | 1 | 0 |
e2 | 1 | 1 | 0 | 0 | 1 |
e3 | 1 | 1 | 0 | 1 | 1 |
e4 | 0 | 1 | 1 | 1 | 0 |
e5 | 0 | 2 | 1 | 0 | 1 |
e6 | 1 | 2 | 0 | 1 | 0 |