i * j + j0 = 0, 0 < i, i * j + j0 < i, abs(j0) < j, i * j + j0 ≤ 0 ⊦
0 < i, i * j + j0 < i, abs(j0) < j, i * j + j0 ≤ 0 ⊦ i * j + j0 = 0
Used formulas: i * j + j0 = 0