1/2 a^{a0,a1}_{c0,c3} b^{c3,a2}_{c1,a3} c^{a4}_{c2} gamma1^{a3}_{a4} a+(c0) a+(c1) a+(c2) a-(a2) a-(a1) a-(a0)
-a^{a0,a3}_{c0,c3} b^{c3,a1}_{c1,a4} c^{a2}_{c2} eta1^{a4}_{a3} a+(c0) a+(c1) a+(c2) a-(a2) a-(a1) a-(a0)