A B C-1 | C S----------+-------- 0 0 0 | 0 0 0 0 1 | 0 1 0 1 0 | 0 1 0 1 1 | 1 0 1 0 0 | 0 1 1 0 1 | 1 0 1 1 0 | 1 0 1 1 1 | 1 1----------+--------
