-4: -4, color(green)(-2), color(green)(-1), color(green)1, color(green)2, 4
2: color(green)(-2), color(green)(-1), color(green)1, color(green)2
color(green)(-2), color(green)(-1), color(green)1, and color(green)2 all work, so take into account the least common factor. That leaves you with -2 because it is the smallest.