3 15 18 a - b *c
a^3 - b^15*c^18
/ 5 6\ / 2 10 12 5 6\ \a - b *c /*\a + b *c + a*b *c /
(a - b^5*c^6)*(a^2 + b^10*c^12 + a*b^5*c^6)