gcd(i, j) * i0 = i1 * gcd(i, j) + j0, gcd(i, j) * i0 = i, i = i1 * gcd(i, j) + j0, abs(j0) < gcd(i, j) ⊦ j0 = 0
Used formulas: gcd(i, j) * i0 = i1 * gcd(i, j) + j0