A^2-b^2-a+b = -b^2+b+a^2-a = -(b-a)*(b+a-1)
x^3-x^2y-xy^2+y^3 = y^3-x*y^2-x^2*y+x^3 = (y-x)^2*(y+x)
a^3+a^2b-ab^2-b^3 = -b^3-a*b^2+a^2*b+a^3 = -(b-a)*(b+a)^2
m^2+2mn+n^2-mb-nb = n^2+(2*m-b)*n+m^2-b*m = (n+m)*(n+m-b)
xc-yc-x^2+2xy-y^2 = -y^2+(2*x-c)*y-x^2+c*x = -(y-x)*(y-x+c)