U | e1 | e2 | e3 | e4 | d |
x1 | 0 | 1 | 2 | 1 | 0 |
x2 | 0 | 2 | 1 | 1 | 1 |
x3 | 1 | 0 | 1 | 1 | 0 |
x4 | 1 | 0 | 1 | 1 | 1 |
x5 | 1 | 1 | 1 | 1 | 0 |
x6 | 1 | 1 | 1 | 1 | 1 |
x7 | 1 | 1 | 0 | 1 | 0 |
x8 | 1 | 1 | 0 | 0 | 1 |